Did you know now is a great time to prune flowering cherries from April to July. This way you stand the best chance of avoiding the disease called silver leaf, which is carried by the wind. After April the sap would be rising rather than falling (pushing out infection).
It is very important to remember that cherries in the group (prunus) are prone to many other fungal disease's which are also damaging.
So in conclusion as long as you prune at the right time of year to suitable growing points and don't over prune then you will have a mass of cherry blossom for many years to come.