It is much quicker to do it here.
Just remember that your pass will be good for only one year from the day you get it activated, not the day that you first use it. Meaning, if you get it activated at 10:30 at night at DTD, that counts as your first day.
Not that this should really be any problem, but if you're planning a trip next year to make use of the pass, it could affect your decision.
RyMickey