Rebounding Foul

[hbioteach]

Team A has the ball and shoots a three point shot. A1 extends both arms and pushes B1 as the ball is in the air.
I'm the lead and call the foul at that point. Ball doesn't go in. B ball.

Any thoughts about waiting to call the foul until the ball comes off the rim or goes in to see if A1 or B1 will have an opportunity to rebound the ball.