I'd do the 'spuirting' at night too! The less-active they are, the better.
2 summers ago, about an hour before our block party, a few of us took it upon ourselves to rid a tree directly over out 'grilling pit' of the nest. Well, doing it at 12pm in the heat of the day was a big mistake! I, for one, was fortunate to only get stung once. The welt was HUGH! The other 2 guys didn't get stung but those hornets were ticked-off.
Take jb's advice to heart or you may end up in the hospital. Close doors and windows and tell your neighbors too if you must. Wear long sleeves, a hat, gloves, and so on. You just never can tell.