Hi yogi02,
Each Testing Facility has its own schedule and available appointment 'slots' - and you can easily research the options by setting up an account at
www.mba.com. That having been said, we're now in "GMAT season", so lots of people are taking (and retaking) the GMAT - meaning that appointments tend to fill up rather quickly at each facility. Thus, if you want to take the GMAT on a specific day and time at some point in the coming months, you will likely have to book that appointment weeks (or even months) in advance.
GMAT assassins aren't born, they're made,
Rich