Really nice set up!
Since quantity is not my primary concern and I don't mind if the plants are smaller, if I do light dep (and I'm hoping I can swing it next year), I'd probably start July 1st. I have trees to the south of my property, and by mid-September there isn't enough direct sunlight to finish some plants, so I'd rather have them flower under stronger July/August sun in warmer dryer air. Also, mid-September the wind starts to pick up out here, and that can really mess with light weight structures. I'd love to wrap the whole thing up real early. Not this year though, batten down the hatches, I'm going to just ride it out this fall.