Hey There, Google and Bing go through what they call a ‘Learning period.’ this learning period is the time that the native platforms take to asses the strategy that you have used, the evaluate your keywords, your ad copy and your landers to assure relevance and that you are creating a good click experience for any prospects. On all google sites they state that the learning period only lasts 2 weeks- but for New campaigns and blowing up entire accounts I always say I need 30-45 days for the learning period to complete and for me to evaluate intial findings and pivot to assure the highest efficiencies. the learning period can be triggered by a multitued of things including changing to a smart bidding strategy, increasing budgets, pausing or activating bulk keywords, the list goes on and on. Just be sure to tell your client that PPC is a marathon, not a sprint, in order to optimize for success there is alot of setting up, waiting to accrue data and then adjusting based on that data.
Hope this helps!