I finally put mine in the ground this year after about 3 years in pots. I had to move around a bunch, so they've been around zones 4-6.
The pots I had them in weren't big enough. The bines would grow to somewhere in the neighborhood of 8'-10', and I haven't had enough cones to make it worth picking them. I recommend putting them in the largest pot you feel you can move around.
You imply that you wont be at your current residence for more than another year or two. If you were going to stay there any longer than that, I would recommend you look into different ways of keeping your hops geographically flexible even after planting them in the ground. I believe that, given enough time, the root crown that grows from an immature plant will put out new rhizomes that you can cut, move and grow. I also think that root systems can be dug up and moved or even split. Something I'm trying this year is growing hops from cuttings.
This video details how one can get hops started in large pots, but I'll also highlight that around the 9:30 mark they start talking about (and showing) digging up an established root crown to give it away / transplant:
These guys are a little obnoxious, but this shows what one could do with a hop crown that has established itself, transplanting and splitting:
This is a thread that I've been participating in, where we discuss how to root cuttings:
Propagation from Cuttings?