Most Google Ads advice tells you what to change. Almost none of it tells you when to change it, or when to read the result. So operators make a tweak, look two days later, see nothing, and tweak again. That constant second-guessing is one of the fastest ways to destroy an account, because every change you make has an impact, positive or negative, and most of the time it lands on the negative side simply because nobody waited long enough to know.

After more than 10 years doing Google Ads full-time and over $150 million in ad spend across e-commerce and lead generation, there is one metric I look at with every single client before I touch anything. It tells me how long to wait before optimising, when to optimise, and how long to leave a change running before I judge it. It is not a vanity number and it is not a guess. It is the real buying window of your business, and getting it right is what makes every optimisation that follows actually work.

1. Find The Report Most People Never Open

The metric lives in a report almost nobody looks at. In your Google Ads account, go to Goals → Measurement → Attribution, then open the report called Path Metrics. This is where you start to see how long it takes someone, from their very first click, to turn into a lead or a sale. And more importantly, how many times they need to interact with your website or your ads before they buy.

Those two numbers, days to convert and visits to convert, quietly set the rules for everything else in the account. Until you know them, you are optimising blind.

2. Set It Up Properly: Conversion, Window, Attribution

The report is only as honest as its settings, so before you read a single number, change three things.

• Fix the conversion action. If it is e-commerce, the conversion should be a sale only. If it is lead generation, it should be a lead, or an offline sales conversion that has been uploaded. It has to be a pure outcome, not an add to cart or an initiate checkout. A pure outcome only.

• Set the look-back window to 90 days. By default it shifts around. I always push it to 90 days because the buying cycle is so different from person to person. Someone may take one day, someone else may take 90. You want the whole data set averaged over that period to get a clear, non-variable picture.

• Change "measure from" to first interaction. It defaults to last interaction. Switch it to first interaction so you actually know how long it takes from the first click, or first ad interaction, all the way through to the purchase.

Get those three wrong and the report lies to you. Get them right and it becomes the most honest read in the account.

3. Read The Two Numbers, Then Time Your Changes

For one business, over the last 90 days on a 90-day look-back window, the journey came in at just under 19 days and around 3.1 visits to the website before a purchase. Knowing that completely changes how you optimise. If a customer takes roughly 19 days from first click to convert, then a change you make today might not show its true result for another 15 to 21 days. I give a little variability on each side, leaning slightly to the sooner end so you stay agile, fast and dynamic, but the point stands: you do not get to judge it in 48 hours.

This is where most people lie to themselves. They make a change, look two days later and ask what the result is, then three days later again. No. You use the data from your own business and your own account to know when the result is actually in. And that window moves. Sometimes it drops, sometimes it jumps, and a lot of it is pure seasonality. Google Ads is brilliant at surfacing this because it is a near-live read on what the market is doing right now. You do not get that from SEO, and you do not get it from Meta. So instead of quoting made-up numbers to your stakeholders or partners, you point at this.

4. Same Business, Different Windows

The reason this matters so much is that the window is never universal. It changes by country, by season and by channel mix, even for the same brand running the same ads.

• US fashion brand vs its Australian twin. The US store averaged around 14.2 days from first click to purchase, stretching to just under 19 during Black Friday week as shoppers held out for an offer. The same brand's Australian store ran at 17 days over 90 days, and 20.6 over the last 30. The visit counts were starker still: 2.3 visits to purchase in the US against 5.2 in Australia, more than double the interactions for the same business. This account has held a 5x return for around three years, yet the timing rules are completely different by market.

• Over-the-counter e-commerce. Transactional goods where people just want the best price and buy fast. From first interaction it averaged around 3.4 days over 90 days, rising to 4.6 in the most recent week. Different businesses carry different benchmarks, which is exactly why you read your own account.

• Heavy Meta spend. Another store showed 18.7 days over 90 days but only 16.4 in Black Friday week. Why shorter? They spend heavily on Meta while we run their Google Ads. The extra retargeting pushes people back to the site sooner and compresses the window.

• Insurance, online vs offline. The offline path, form to call to sale, ran around 4.7 days and three interactions. The online self-serve path was slower at 7.8 days and 3.2 interactions. They had been trying to push people online to self-serve, yet the data showed online buyers take nearly twice as long to act. An important reality check on the strategy.

One caveat on the report: there is a "bought within one day" percentage, but I do not lean on it. Cookie and pixel limitations mean some returning buyers get logged as a first interaction, so that figure can mislead.

5. Turn The Window Into Strategy

If it takes multiple visits before someone buys, then a single click is rarely the whole story. People come back again and again to look around and shop around. If someone visits, likes what they see, then disappears, and you do nothing to bring them back for that second or third visit, you miss the sale.

That is where the number becomes a strategy. You get deliberate about every channel that brings people back: Performance Max remarketing, display remarketing, Meta, Instagram and YouTube remarketing, and email marketing. Anything that nudges a visitor back to the site moves them closer to the purchase, and as the Meta example showed, it physically shortens the buying window. The metric does not just tell you when to optimise. It tells you how hard you need to work the middle and bottom of the funnel.

The Bottom Line

Optimising a Google Ads account is not about reacting faster. It is about reacting at the right time. Open the Path Metrics report. Set a pure-outcome conversion, a 90-day window and first-interaction attribution. Read the two numbers that matter, days to convert and visits to convert, then judge every change against your real buying window, not your impatience.

Do this and you stop killing changes before they have had a chance to work. Skip it and you will keep tweaking on a two-day timer, burning budget and momentum while the real result was always three weeks away. Most content tells you what to change. This metric tells you when, and that is the harder, more valuable half of the game.