First question where are you?
My neighbors are picking.
For this area (south Wisconsin) I have picked my Itasca and picked Marquette for a local vineyard. to me the break point where you have to is that lots of damage is happening as with the yellow jacket wasps or woolly bear Beatles, ,,,,, OR I have time since it is a weekend, ,,,,, or the press is ready for the next run, ,,, OR ? ,,,, ie there isn’t a magic point, just a range.
2019 I picked and ran two week over ripe Itasca for a club member who was in the hospital. The yield was poor with raisins but he sprays lots so bug damage wasn’t bad.