I would cure the rock from 80-82. The cycle will go quicker warmer, but you want to maximize the life on the rock, so keep it warm, but not too warm. Also do plenty of water changes and plenty of water flow. Monitor the rock and if you see signs of fouling scrub it off, rinse it and put it back in the bin.
It is a pain, but IMO
, you usually get the best life on the rock curing it youself.