Once you've paid $200 to PearsonVue and received your ATT, it is best you schedule as soon as you can because the slots get taken up quickly. You can always check PearsonVue to reschedule, as slots become available when someone cancels or reschedules.
NCLEX Testing with Pearson VUE Here's the website for PearsonVue. Yes, it's very easy to reschedule. Once you've paid $200 to PearsonVue, you can view what's available for various months, days within specific months and time for specific days.