+1I used to go every afternoon on weekdays on my way back from class, and they were playing most days. There are no guarantees, but try sometime between 3-5. Worst case you will see a few guys doing individual drills, best case they will be running full court.
Now is the best time to go, because once the official practices start they really don't want anyone in there (there were several times where I was asked to leave) which is understandable.