My personal preference is always to get my trees into their permanent home as soon as possible and give them as good a start as I can through mushroom teas,
compost teas, top dressing of compost and I like to add dissolved vitamins at the outer edge of the root mass.
I can always set up a temporary protection bubble for those days the weather could harm the new trees.
Once I have them well established, I tend to leave them to their own devices and if they should die, I find something that will work better for that space.
Redhawk