How to harvest leaves
How old should a soursop tree be before harvesting the leaves?
Certified GKH Gardening Expert
You can do this as young as 2 years. If you are pruning or shaping the tree anyways, then what you cut off can be used. It is best not to take more than 1/3 of the tree or its leaves at one time, though.
This article will give you more information on the care of these: https://www.gardeningknowhow.com/edible/fruits/soursop/soursop-tree-care.htm