Cincturing Lychees: In order to stimulate good fruiting on a lychee tree you need to cincture a large limb; not a small branch and the correct time to do this is at the end of summer to early autumn. If you take air layers at this time, they can flower but this is counterproductive to roots forming on the air layers so take these flowers off. The cincturing only affects the limb you are girdling, not the whole tree.
Don’t over-fertilize your lychee in the ground – just give a little and often. The sensitivity of young lychee airlayers to fertilizer isn't obvious unless you have killed them or somebody has told you about it. I'm not talking about overfertilization, just the same dose we give to everything else, and slow release at that.