How long should I leave a new Facebook ad campaign alone, and what should I check first?
Votel recommends not logging in and changing things for about seven days. Every change can restart your ads in learning mode, and Ads Manager is not a day trading platform.
After seven days, check one thing first, and maybe only that: cost per result (for a sales objective, the cost per sale). Only if you have no results should you look at other columns, such as which ad had the highest click-through rate or engagement and which ad Facebook favored by spend, and read what that ad's message said.
If the cost per result is one you are happy or nearly happy with, let it run. If not, add more ads: in the ads tab, turn off the ads with a poor cost per result, add new ones, and repeat, perhaps once a week or once a month, until you are left with your best performers.
Make sure the experience from ad to landing page to sign-up feels like one company, with matching colors, branding and domain. Feeling like you left for another site causes drop-off.