Another college professor. We are required to use an e book but I encourage students to purchase a hard copy instead if possible.
I also expect students to have the textbook within a week of our first meeting.

https://www.insidehighered.com/digital-learning/article/2017/08/16/which-better-reading-print-or-screen

Professor here. I post a lot of readings online, and typically assign a couple books (but I’m in the humanities, so these are widely available non-fiction books, not textbooks or lab books). I almost never place my book orders with the campus bookstore because i assume students just buy books online. I’m fine if they wait until the first day of class to buy books (though the syllabus is typically available online ahead of time, so they can certainly buy earlier). If they wait until the first day of class to order, I expect them to use amazon prime or the like because they will need to be reading from the books by the second week of class.

Now that I post this, I think I should go back to placing my order with the campus bookstore, just to give students options, even if they never exercise that option.

^He is also taking advantage of the tax free holiday to get binders/notebooks/paper, etc. At some point, he'll get his binders set up for each class. It'll be one less thing to worry about doing once he gets there.

Also, this is a good weekend to get backpacks.

Check their university account. My son had a list of books with the option to rent/buy used/buy new for most of them, some could only be bought new. He checked off what he needed, placed the order and had them shipped to him (he also had the option of picking them up at the bookstore).

I think there is one more book that he needs to get closer to the start of school.

For what it's worth, it's currently tax-free weekend in Virginia, even with online purchases. Books are included, but only up to $100. If there are any books that come in less than that price and are ones you feel you can just get right now, go for it.

Also, sometimes there is an independent bookstore alternative near campus that stocks textbooks.
Labyrinth @ Princeton and Seminary Co-op @ UChicago are two examples I’m familiar with. Each has a discount or rebate program. If price/availability is the same, DC tends to go to the indie rather than the official B&N-run bookstore. Loves the rest of what they offer (books and programming) and wants to help keep them there.