Pot-bound plant in a tiny grow box

I transplanted my plant from a solo cup to a one gallon pot 10 days ago but I can already see quite a few roots through the drainage holes and there's a lot more today than yesterday.

The weird thing is my plant is really short (less than 3 inches) but I think it's about to take off.

So should I still change the pot already?

I think you should let the plant grow more before transplanting. MJ will grow roots to the edge of the pot and down to the bottom fast. Let her sit a while and get comfy.