I would stock them as soon as possible being aware that handling and hauling fish in hot weather stresses them a lot more than in cooler weather.
If you are going to get them off a fish truck that have been on the truck for five days maybe summer is not such a good idea. If you can get them directly from the fish farm with a reasonably short distance to your pond I see no problem. The fish farm may not want to harvest them in stressful hot weather. A reputable fish farm should be able to tell you if what you want and the distance you need to travel with the fish is ok to do now. They should tell you if you need to wait till cooler weather.
The hot weather of summer is not the best time to handle fish. Higher stress levels. That said, it still might be a better option than waiting and having to buy larger fish.
The experts should have better advice than me. I am just repeating what I have learned here on PBF. Only fish I transfer in hot weather is from one of my ponds to another and I have had no problem doing that in the summer. Hauling them in a truck or bag for hours on end might be a different deal though.
Last edited by snrub; 07/05/16 11:41 PM.