If your hunting, your most likely going to be making cold bore shots, so your rifle should be shot in using cold bore technique....not rapid, or even slow 3 or 5 shot groups, but cold bore grouping.
As we do it at the shop, and really, it is a pain, but hey, were getting paid for it, if your cold, un-fired barrel is, let's say, 77 degrees when you send the first shot through it, then you should let your barrel cool back to 77 degrees before the next shot, plain and simple.
Using this method will guarantee your grouping is reflecting 'cold bore' characteristics, there will be no question what your rig will do with the barrel at that temperature, it is a good idea to sight in at temperatures as close to those you will be operating in!
On a 95 degree day with 70% humidity, while at an outdoor range, the average thin sporter barreled 308 may take 30 minutes or 'longer' to cool between shots, to allow the barrel temperature to return to the temperature you started with.
Allow yourself plenty of time, and enjoy the surroundings while at the range!
After you have established your 'cold bore' zero, then the fun begins with seeing what your rifle will do while firing slow and fast shot groups. Seeing what your rifle will do when it heats up!
And remember to record all of this discrepancy for future use!
Have fun!