Harriet, generally, the more leaves you leave on a young plant, the faster it is able to develop its new root system following transplant. So a light touch is called for. You have the entirety of the plant's life to do your pruning, so why not give it the best chance at establishment possible....by leaving as much foliage on it as you can?

If you or anyone else is interested, I can explain the science behind this. But for now, I'm leaving it there.

+oM

Jumping in, I need to transplant a small crape myrtle tree, just waiting until it is a little cooler and it is in a more dorment state.

It is 3 times as wide (bushy) as it is tall and I have wondered how much I should cut it at time of transplant. It should not have many leaves, it has lost half already (but it is still warm here, high 80's)

It is only 3 feet tall at the most, but it has long branches .. Recent pic showing how it has lost its blooms and leaves

Hey sweet monkey, again, there is no imperative that pruning be performed at all at time of planting. That's a myth that needs to go away. So, just to elaborate slightly on my above comments, it's happenings in the branch tips-at the terminal buds-that influence root system development. I think we can all agree, a newly-transplanted plant needs to regrow a root system, so this is and should be priority number one. I won't science you guys out too bad here this morning but it is plant growth hormones called auxins-again, produced in branch tips-that exert an influence on roots to grow, so we don't want to arbitrarily be removing lots of branch tips, especially out of some misguided notion that the plant "needs" this to happen. It doesn't, and again, there are years ahead to do your pruning.

+oM