visa appt dates

[smithamc]

ihad been checking visa appt availabilty from a long time to prepone my appt from apr to march. on friday morning(20th jan) i saw some dates open in march, i tried to reschedule, the dates were not in the calender. from friday i am seeing they are opening up availability calender for may almost 5-6 times a day, it gets filled again they open from may 1st. how is it possible? can we really rely on these dates.
any input will be appreciated.
thanks

[immihelp]

Dates get filled quickly because lot of people are trying to take the appointments.

[VisaChief001]

You can reschedule with the actual calendar. Avaliablity calendar dates you may not get it.