it sucks, but for me in my climate it's pretty normal(had some late plants last year that experienced non-stop rain/drizzle for at least the last month)
check every day, and look for leaves sticking out of a bud that look a bit wilted or discolored. if you see any such leaves, pull it: if it comes loose easily, you've probably got budrot. fold/push open the bud at that spot and check where the rot is. usually it starts somewhere inside, close to the stem, and by looking for slightly wilted leaves you can often spot it in the early stage, and cut it out before it spreads.
a trick I've heard, but not actually used myself yet, is to dip the scissors you use in vinegar to kill the mold on the scissors, so you don't infect a new spot when you make a cut(I did however do disinfection with a torch lighter, going over the cutting edge of the blade between cuts, but vinegar seems more convenient).
especially after you first spot budrot, keep checking every day. some plants handle it quiet ok and don't get any rot, or take a while of bad weather to develop any. but once the first rot is spotted, it usually keep re-appearing, potentially every day multiple spots if it stays rainy, and you have to keep a close eye on it or you'll lose a lot.