Think of it as live fish that have been holding their breath for the entire time of shipment. Get it in the tank ASAP
Whatever filtration you've been running that got your tank through this cycle....leave it alone. As soon as that rock hits, that filtration will be put to an immediate test.
You might consider adding some sort of bio-load on the tank for a a week in advance. Something like a dead shrimp. That way, you'll have super numerous bacteria ready to do the job.
I'm assuming that there is nothing living in the tank at this time.