You still have some shucks (flower remnants) left there so the PC is not attacking quite yet, but it is a good time to start laying down the coats. You want to do a bunch of coats at the start to get a good layer and you can start it now so there will be some friction present right when the first shucks fall. The only exception is if 1" of rain is coming soon, in that case hold off as your work will be for nothing. If you spray now, when the shucks fall the fruitlets will be naked which is not good, but the Surround on the limbs will still be there to slow the curc down a lot. On nectarines and plums not much Surround sticks to the fruitlets anyway, it is mostly the spray on the smaller limbs that slows the curc down. Curcs want to fly as little as possible, it uses up too much energy.
I am almost that far along on my apricots and plums, and was planning on laying down my first coat this weekend.