I suppose it would add something to do besides tracking but I have several concerns with it. First, the coach should be required to have a season remaining to early recruit. Then once the coach uses his first recruiting tool (phone call, letter, HV, whatever) he should be locked out of promotion or transfer after the season. Also, he should be locked out of transferring the season to another team.
The reason for these restrictions is to prevent a coach from spending his replacements money on players the new coach may not be interested in. Plus, some coaches would potentially spend all available money on trash players and then drop the team. Neither situation is good for the game.
Early recruiting would be a risk/reward situation because due to broken promises, transfers due to lack of playing time, or early entry into the draft you can't always be sure which players will return the following season. With early recruiting, a coach may think he wants a PG and spends all available cash on one. Then when he unexpectedly loses a SF or PF/C he may be short of cash to fill that greater need. In addition, there is no guarantee that a sim school won't jump on the early entry prospect and set up a real dilemma for the coach.
These are my thoughts on this subject. I know a lot of coaches are in favor of this idea but I am not convinced that it will add anything that can't be accomplished during normal recruiting.