We do von Frey and Hargreaves on mice.
For von Frey, 3-4 days of acclimation before testing and usually 3 hours each day. At the end of three hours, most of the mice would be sitting still, either grooming or just sitting there. Then on testing days, I would still acclimate them until they are mostly sitting still. Most times it would be somewhere between 1.5-2 hours, but sometimes still 3 hours.
I have tried to sit in the room with the mice for the the last hour of acclimation, in order to avoid their reaction to me as a novel object entering the room.
We usually do Hargreaves after von Frey in the same room on the same day. So we also acclimate the mice to hargreaves once or twice before testing days. 30-45 min acclimation on Hargreaves at 30 degrees Celsius usually is sufficient. Occasionally, in the very beginning of acclimation phase, it could take longer than an hour for mice to settle on Hargreaves. On testing days, I gave the mice 30 min for acclimating on Hargreaves.
They do fall asleep on the 30 degrees platform. To avoid stimulating them in sleep, I try to make some tiny noises or movements to see if their ears or whiskers move. If they don’t move, then I wouldn’t stimulate them.