Could we Prepone a Visa appointment ?

[vasudevadv]

When i searched on internet about rescheduling a visa appointment, it says "You can reschedule your appointment (for a future date only) and up to a maximum of two times. If you are late or have missed your appointment on the scheduled day, the system will not allow you to reschedule or cancel, and you will be required to book a new appointment after 24 hours."

Is it allowed only to book a slot for FUTURE dates? What is there could be a cancellation and an appointment is open ? Could we not prepone it??

[arunamani07]

It will show us slots whenever available after or before n we could book..max 2 times allowed i guess