toadman,
Don't add anything to the soil. Ever. Not for trees.
You are probably wondering why.
Lets take a tree that grows at least 20 feet, like your cherry.
You add compost, garden soil, then plant it.
As it grows, it will grow the roots all around the compsted soil and garden soil you add.
But at some point, the roots will have to grow out in your sandy soil to support the size of the tree.
It won't do this.
Believe me, it will just keep the roots in the delicious soil that you added.
What happens 5 years from now in a bad wind storm?
THe tree has no support, the roots never grew beyond your amendments, they were discouraged from doing that.
Just dig your hole, plant your tree, not deeper than the soil line, and mulch real good.
Make sure you water it real good every day for a week, and then taper it off.
When you water it good every day, the roots will move easier to take hold and dig in.
DO NOT EVER FEED YOUR TREES.
Mulch and water is all they need.
My soil is sandy too, which means you must water them in the heat of the summer more than other people water them.
If you feed your trees, they will grow fast and the growth will be weak.
Congrats on your new trees.