ok... first of all. You should really use the help forums for this.
and i may get in trouble, but ill answer your question here.
Training happens early friday morning, no stats or training will be recived from the player untill then, so you can switch it many times and there will be no affect.
Training: im assuming yopu set jumpshot for point guard. If so, then you need to wait for your games. Your player recieves training based on minutes played in the week (not counting PL). for full training, you want to get over 48 minutes a week, dont go too high (past 75) or it will affect his game shape. So play him as a starter this game and next game, and he should have enough training minutes for friday's training. This will also train any backup PG's, but they probably wont recieve as much training because they didnt have a full 48 minutes.
No names listed in the rtraining menu cause there have been no games yet, well there will be 15 minutes after i post this, but none as im writing it. Hope that helped
And once more, next time please use the help forum.