One of the advantages of being self-employed/sex work is you can work as much or as little as you prefer. I don't know your set up, but if your health is unpredictable I would probably avoid bookings made well in advance, but on a day when you feel OK, go for it and try and do as many bookings as possible.
I'd also advise being sensible about scheduling, i.e. make sure you have 1-2 days a week totally off, or e.g. don't work mornings or nights depending on your body clock etc. I think it's a case of being pragmatic about what you can and can't do.