White Nanking cherries insect protection?

I finally got my hands on some white Nanking bushes. I know nankings are highly disease prone and unfortunately get attacked by fruit flies but how does everyone protect them and how early in the fruiting process do they need protection? Is it just once the fruits start ripening?

Are you sure your issue is fruit flies? Those are attracted to rotting fruit and don’t usually bother the fresh stuff.

The first step would be to identify the threat so it can be properly addressed. In places with insect pressure the first line of defense thend to be a dormant oil application like Neem oil, it takes care of overwhelming eggs of many baddies without affecting the good guys.