"The Draft includes players on 2000 opening rosters (first season)AND players already on the list. "

If I read Mike's explanation correctly, once opening rosters are set the rookie pool is set. If that is true, there is no advantage to waiting for a later date. Any rookies called up after opening day will not be avialiable until the Monthly draft anyway.

If I understand this correctly, I think the sooner after opening day rosters are set the better.