how big is it now ...

you want to do it while it is fully dormant ... to avoid stressing out leaves ....

you want a potting media with very high drainage ... either a typical peat mix.. mixed about half with mini chunks ... or a cactus mix ...

you want water in the top.. and nearly all of it out the bottom ...

since i dont know the size.. i can not tell you what size pot..

and a pic would sure set us up for giving you precise advice ... check out the link for how-to

when the time come.. you take a hose.. and blast all the soil off .. no need to be careful about it ... and while you have it nudey ... you trim any root problems ... its all normal.. when bare rooting a DORMANT tree ...

what zone are you.. in my z5 MI.. i would shot for about 4/1 ... so i could leave it outside.. after the potting ... and let ma nature bring it out of dormancy at the right time ...

more info please... you are early to do it.. but right on time to be learning when and how to do it...

ken

Here is a link that might be useful: link

I think you will find this link extremely informative regarding potting medium: Al's Comments on Container Soils - Water Movement & Retention

and

this link should answer some general questions about transplanting (I'm wondering if you have kept the root system straightened out with previous replanting): Planting a Tree or Shrub.

Avoid peat-based mixes.

Check Brandon's link to Al's thread on container soils. That would be best for your tree.

When I re-pot, I try to catch my trees while they're quiescent still, just before the
buds begin to move. With the proper timing, trees don't skip a beat.

Josh

I used to grow and propagate a lot of woody stock in the size range you are describing. I'm going to link you to an excellent article with some data I think you'll find useful in many respects. In particular I think you need to read the sections on evaluating root balls for correctable conditions when you are moving them to larger containers. This is the time to do it. Container stock should be bumped up before it is so root bound that the roots literally form a shell or encapsulation. If this has occured, it is correctable and this article shows you how to remedy the situation, unless they are so totally large and distorted you have impacted it past the point of no return. It's very important to chose the right container size when bumping up. This is going to be determined by a lot of factors. But you don't want to go from too small to too large. Hope this helps. BTW, small container woody stock does not necessarily have to be done in dormancy. It need to be done, when it needs to be done. LOL. This is meant for pros, but I think it's written where anyone who has a basic knowledge of growing can understand it well.

Here is a link that might be useful: UFL woody stock production