I would wait for the beginning of the next season. I mean if you create your second team right now , you are losing I think 3 Fridays ( 3 training days). In my opinion , when I have 18-19 year olds for training I want them to get every training they can possibly get. On the other side most likely you are not going to have a player with MVP potential or higher so those 3 trainings you would miss ain't gonna hurt that bad.
Soooo it's up to you :)