I always got the tank a day or two ahead of and fish purchase, especially if the local water is clorinated. I always tried to use bottled or spring (not distilled)water, if my tank wasn't too big.
I'm sure you will enjoy him.
I got 2 gallons of drinking water to start. I have a brita pitcher, so I'll run my tap water through that when I do the changes. I wanted the gallon jugs so that I can fill them and let them sit to get to room temperature when I'm ready to change the water.