My wife was in excellent health right before, super energetic, and exercised a lot - the doctor even wrote a letter saying that she was among the best candidates for major surgery he'd ever treated. She was still knocked flat for most of the 4 weeks (and it was an unpleasant surprise!). However, she does think that she got back to normal faster and with fewer issues because she'd worked so hard to be fit and ready beforehand.
Also, dilation in a bathroom might be possible, depending on your flexibility, but it is NOT recommended for that first month. At that point it's still an open surgical site, and getting bathroom bacteria in or around there is a truly terrible idea. Also, waiting too long between dilations when it's "new" will often mean that the vagina will actually start to heal closed slightly before the next session. It's not necessarily a dealbreaker, but it's not a great idea.
Is there any way for you to go home at lunchtime? Honestly, that ended up being the only way my wife could swing it for the remainder of the first month (Brassard recommends 4X daily for 20 minutes for month 1, then 3X daily for 30 minutes for 2 months, etc. but other doctors' schedules obviously vary).