Since you have a year or 2, why not buy the 3 gallon size tree? It's cheaper and easier to drive with. If I were you, just get those 55 gallon drum, cut in half (make it a 25 gallon pot), drill some holes at the bottom, and create loop handle on both side using very thick paracord. Put the 3 gallon size tree into the half drum and grow it for next two years then you can put in ground.
Depends on the tree (air layer, grafted etc), I put my 3 gallon size Maha tree into the ground mid last year, this spring it has flowers and tiny fruit, I had to pinch the fruit off so that the energy goes to create more bush.