I'll never say I do it the correct way, but I usually keep about 50 gallons of water made up at all times.... I have my water vat which is nothing more than a rubbermaid trash can and has bulkheads drilled in bottom and near top and run an Iwaki pump 40RLT to circulate the water!!!! Kinda an overkill, but I had it laying around so I use it...
Letting the water come to room temp is ok, but I also use a heater since they aren't expensive, and try to get it the same as my tank water.... Tank usually stays around 79-80 so in that range I have the heater set, but then I also use a therometer to double check the display and water vat as well. I will do this before water change just to make sure everything is pretty close.....