Just leave the bags on until you return home. The self pollenized blossoms won't have very large tomatoes in that short time so plenty of time to remove the bags at a later time.

(I mean, I realize they stay on from before the blossoms open, until the blossoms fall off, but just how long is that?)

The blossoms don't always fall off and you can see the remnants of the blossoms at the blossom end of the maturing fruits. And that's just fine. No way to predict any timing since, as I said, often times the blossoms don't fall off.

Carolyn

Thanks! I'll go finish up them. I'm so happy today. After two weeks of temps in the mid to high nineties, with heat index ratings of 110 +, today is only 78 with a nice cool breeze. I'm loving being outside this morning.

You just have to take them off before the tomatoes get too big inside to get the bag off. Often times you will have several fairly large fruits growing inside the bag and more buds still opening.