Missing enrollment deadlines could cause you not to be accepted and prevent class registration, so keep a close eye on those fast approaching deadlines!
Always make sure that all paperwork is submitted at least three months in advance of the time that you plan to be enrolled. Certain schools have specific deadlines, which you can likely find on their individual websites, but just remember the sooner you submit your paperwork, the better. There is no harm in having your paperwork in first; early submission can only help you.
For Fall enrollment, have all of your paperwork in by July 1
For Spring enrollment, have all of your paperwork in by November 1