elm soil

So I couldn't resist picking up this Dwarf Elm from a roadside nursery but had to quickly treat a minor case of scale with some oil spray after scraping them off. Otherwise looks really healthy and totally rootbound. Looking to repot asap. Would it be safe to do so now or wait till spring...

Tried to find this topic, but couldn’t find an answer. If this has been discussed (which I bet it has) then I apologize. Where do you guys buy your soil components? At first I bought those expensive “bonsai soil” packs, but the more trees I get or make the more I look for cheaper options. I‘ve...