i Believe people wait until pea-size fruit develop, to start thinning.

there are many topics about this, just do a quick search on this site or google..

If you try thinning the blooms you are very likely to accidently piss off some bees. Also, a bloom isn't a fruit unless it's pollinated. For apples you thin the clusters by leaving the best looking fruit and removing the rest. I don't know if that differentiation would exist for the blooms.

Citrus trees are self thining, A citrus tree will retain only the amount of fruit that it is capable to bring to maturity.