It's critical that you understand how Facebook reports conversions. It will prevent lots of confusion.
By default, Facebook will report on anyone who converts within 7 days of clicking your ad or 1 day of viewing (and not clicking).
Of course, you can also change the attribution setting to 7-day click only, 1-day click only, or 1-day click and view. If you do that, the reporting will be based on that.
And you can also compare attribution to see MORE conversions that came in outside of those predefined windows.
Finally, it's often assumed that two ads can get credit for a conversion, thereby inflating numbers. This is false. Credit goes to the most recent click (if no click, the view).
