Find First Pawn in Sphere Overlap

I need to get all pawns inside of a sphere overlap and then figure out which pawn entered the sphere overlap first, however if that first pawn leaves the sphere overlap then I need to get the next pawn that had entered the overlap. Basically it’s just a tower from a tower defense game and I just need to make sure it prioritizes the correct target.
I’ve been trying to figure out the best way to go about doing this and I just can’t seem to figure out what I need to do.

You could add a Sphere component and react to OnComponentBeginOverlap and OnComponentEndOverlap. Add the pawns to an array when they enter the sphere and remove them when they leave or die. The first pawn in the array is always the one among the ones still in range that entered first.

Note that this system will only work if all pawns have the same speed. If they have different speed, you might want to target the fastest ones first.