there is no such thing as an official rollover date.
Rollover could be done automatically by the charting software, or trading platform.
Do note that automatic rollover could be done poorly (see below).
you can roll over anytime you want.
Better roll over when the further month's contract volume is higher than the front month's contract.
depending on the products,
you roll over a day before expiration (eg some European index futures).
or you roll over a few days/weeks before
for ES/NQ .... typically you can roll over tomorrow, Friday.
for gold/corn/copper/currency /other indexes/bonds ... futures, rollover based on what I said earlier.