I think I'd move it right now unless you want to leave it till next winter...It'll be starting into growth already and really it's best to do it when it's dormant. Depends how desperate you are to move it and whether you can wait till the end of the year, I certainly wouldn't leave it any longer than right now if you want it moved before summer.

I agree with you Louisa, I actually moved one last week but I had put a hessian sack where I was going to plant it a week before to warm the ground up a bit.