You take your own risk

In theory, you cannot use that AP, since when you leave US, the AP didn't exist.

But some people did that, leave before AP approval and relative send the approved AP to him abroad and he uses it to enter US. This depends on that the immigration officer at the port is careless, meaning they didn't check the approval date of AP and the date the guy left US.

So, if you meet a responsible officer, he will find out that when you leave, the AP is not approved, and then you will be in big trouble. My guess is that if evreything else is fine, they will still let you in, but leave a bad record on the system, and no one knows what that will do in the future. Or worse, they will dismiss your whole 485 cases, though less likely.

Thus, judge and take your own risk.