Hello, and welcome to the Forums.
Most deciduous fruit trees, including Cherries (Prunus avium) should be pruned annually. This is often done towards the end of dormancy in Winter. However some growers in some climates also have good success with pruning immediately after harvest in late Summer. I happen to be among this latter group, and do most of my fruit tree pruning post harvest. In a wet summer climate there may be an increased risk of disease with Summer pruning, though it still does need to be done in some situations.
Do you know the cultivars of your tree, preferably both the fruiting scion and the rootstock? I am curious if the rootstock is intended to promote dwarfing. Perhaps no matter, pruning is what will ultimately determine the size of your tree.