I think it depends on how available you'll be to stop in and check on things once the kids are back in school and you're back to work. If your fall schedule is such that you'll be out of the house and an hour away before the contractor gets there, and not home until after he's gone, I don't think I'd wait until fall. If it were me, I'd want to do it during the summer, while I'm around to keep an eye on things and make quick decisions when presented with them. But I'm a bit of a control freak.

Also, I don't know the scope of your work, but it shouldn't be as noisy as, say, framing and roofing a new build. There will be noise with demo, and with whatever small amount of carpentry and drywall has to be done. The noisiest will likely be the tile saw, but you might be able to have that set up outside.

I'd say you should just get it done, you've been planning it for 10 years! A bathroom remodel, even a major one shouldn't take longer than a week, he'll be in and out.

If you didn't have other bathrooms to use, then it would be a different story.

Get it down now while you are available to make the decisions on site. Or, wait until the fall, but add another 3 weeks to the timetable to account for the times that the contractor needed a response from you but your schedule wouldn't let that happen so he moved on to another project to keep his workers busy.