Setting Initial Possession Arrow?

[vawils]

This is a common occurence that I am still not 100% certain of the correct call so appreciate some feedback:

On the initial jump ball, A1 clearly taps the ball to the sideline out of bounds. Obviously the ball goes to B1 for a throw in. Question is: should the arrow also go to B since it could be interpreted that A1 had first possession and tapped it out of bounds therefore next possession change should also go to B. Or should the arrow go to A since no real first possession by A? I think the latter ...... Thanks