The official rules require a 30 day notification before any attempt
From here:
6. Entrants must specify and provide the ANSARI X PRIZE Rules Committee with their take-off and landing location, and the date of their launch, not less than 30 days prior to any flight attempt.
Recently, I read that they may have changed it to a 60 day notification, but I honestly don't know if that's correct or why they might change the rule.
OT: Here's an interesting list of major donors towards the $10 million prize.