You only "need" one graduate to hold enough developer to fill the tank.
Soon as I fill the tank with developer and finish initial agitation, I rinse out my only 32-ounce graduate and start to fill it with water that I will add a few cc of stop bath to...
But it wouldn't hurt to have two more, separate graduates for stop bath and fixer, so you don't have to juggle.
I tend to put my stock developer and fixer bottles in a larger tub of water to get to temperature. The developer gets mixed 1:1 at the last minute, with running water that is already up to temperature.