Thanks for reaching out–ads won't show up instantly as YouTube is still updating your channel to the YPP. Also, make sure that you've enabled the monetization of your videos. Learn more here: https://yt.be/help/7KRY
Good question–since it's the system that's adapting, ads should be up within a couple of days. However–if you would want to have an in depth analysis for your channel regarding your monetization, you may reach out to our Creator Support Team here: ttps://yt.be/help/partners