Great idea to revive this post now while the application period is open for both sessions. I am not sure there is any preference given to the early applicants over the later ones, but better to get it in early to be on the list. And remember there is no guarantee of even getting invited to tryout, but they refund the money if a kid is not selected.
Reading back over my posts above, I see they ended in 12/2016 before my 2017 knew his fate. He was so fortunate to get the chance to pitch in the Senior Academic game, and he did well enough that he drew significant interest similar to what TIH's son experienced. In the end, it was being seen at this game that was the deciding factor in his opportunity to attend a high academic D2 program and become a part of the team as a PO.
His experience was for the Senior game (we did not know about the Junior game), and there is definitely the advantage of having the strong test scores already done versus the Juniors who may just be able to point to GPA. But as TIH said, it cannot be understated that the kids who get a chance to play in these games have an edge because their strong academic credentials reduce admissions and ongoing survival risks for coaches. I highly recommend pursuing the tryouts if your son meets the criteria.