Right now, there are a couple of options:
1. Schedule the book for Monday and Tuesday this week, then edit the schedule at the end of the week to be on Wednesday.
2. Use the division selector to schedule multiple copies of the book that Start After each other. For example, schedule one copy of the book with only chapters 1 and 2 for Monday and Tuesday; then schedule a second copy of the book with chapter 3 for Wednesday, which is set to Start After the first copy. You’d schedule one copy for each time the schedule changes. If you schedule multiple copies of the same book, the Scheduler will tell you which divisions are scheduled for each copy so you can see which copy is which.
And yes, more flexible scheduling options are on our list of ideas to consider adding in future updates. 🙂