It is best to transplant when the trees are dormant. I prefer fall because they new roots will be going into their new home as soon as they start to grow inthe spring.

Having said that, depending where you are, if soil temps haven't hit 45-50 degrees yet, the roots haven't started to grow.

Make sure you get a big enough ball. That is tough without a spade. Rough rule of thumb: measure the diameter of the tree 6" from the ground. This is called the "caliper". You want to start with a 12" diameter root ball PLUS 10-12" of root ball diameter for each inch of tree caliper. Or, you could bare-root it...if you have a rather large air compressor and a AirKnife or AirSpade

Next tip, find the root collar (where the trunk flares out into roots). Make sure that is at ground level. There are a LOT of trees planted too deep - actually coming too deep from the nursery, then planted deeper in the landscape. This significantly shortens the life of the tree...if you see trees in the landscape dying when they are 6-10" in diameter, I'd bet it was a planting depth issue.

Watering - bare minimum: 5 gallons, plus 5 gallons per inch of caliper per week. I'd rather see that much twice per week. Drop one of those waterings for each 1/2" of rain within the week.