The first results depend on several factors, such as the size and type of your product range, the traffic of your store or the ad formats you run. When the results are reliable enough to evaluate is not set by the calendar, but mainly by the number of orders your campaigns collect.
That is why you should judge the results over a longer period, usually a month, not by the first days. At the start, campaigns go through a learning phase during which performance is less stable. Read more in the article What is Learning phase in Campaigns?
💡 Recommendation:
To start, run PMax campaigns on Google and keep enough credit. For the first month we recommend €200, so the system can collect data for optimisation.