I think you would be fine. The ground won't freeze for quite a while yet. Just keep some moisture on the roots.

It'll be better off in the ground than in the pot, as long as it's not a terribly exposed spot, and if you don't cut into the root ball. I'd find a temporary spot on the south side of a building where it'll get some sun during the day, and also be sheltered from the worst of the northwest winds. (Wind chill matters a lot.) When the plant comes out of the pot, DON'T separate or cut the roots as you would do in the spring. It's too cold now for any significant regeneration, so that would be trauma with no benefit. I'd also mulch it really well, to 4" or more. If you don't have any mulch left on hand, put a layer of newspaper or black plastic trash bags on the ground around the base of the plant, weighed down with rocks or bricks. You'll still be able to water, and should until at least Thanksgiving to keep it hydrated in preparation to withstand the hard frosts that are coming. In the spring, wait until new growth is up a couple of inches or more before moving it to its permanent location. If it was root bound coming out of the pot, THAT will be the time to cut into the roots and spread them a bit. It will need water a couple of times a week next year to help it get really established.