See IRS Publication 970. On page 13, we have the section titled "What expenses qualify".
The school is obligated to send you the 1098-T to document you paid the tuition bill. The AOTC (American Opportunity Tax Credit) offers a $2500 credit (not a 'tax deduction', but a direct reduction of tax owed, a credit) for $4000 worth of higher education expenses. For most situations, $4000 for the first semester of school will be no issue, the billed tuition, likely covers this.
If not, "expenses for books, supplies, and equipment needed for a course of study are included in qualified education expenses whether or not the materials are purchased from the educational institution."
The IRS pub offers an interesting anecdote
Grace and William, both first-year students at College W, are required
to have certain books and other reading materials to use in their
mandatory first-year classes. The college has no policy about how
students should obtain these materials, but any student who purchases
them from College W's bookstore will receive a bill directly from the
college. William bought his books from a friend; Grace bought hers at
College W's bookstore. Both are qualified education expenses for the
American opportunity credit.
This leads me to advise that if you need to use these expenses, contemporaneous notes should suffice. For books or expenses purchased by check or credit card, keep those bills/receipts. For these cash purchases, the day, date, book title, class used for, and cost would impress any agent auditing you, should that occur.
Last - keep in mind, the tax code doesn't allow double dipping here. I am in the exact same timing as you, freshman student this year. When I went to pay her tuition, I was about to pay the bill via our 529 account, and after reading Pub 790, realized I'd lose the $2500 credit if I did that. To get the credit, I had to be sure to pay $4000 in cash. I realize that for 2017, the transactions are behind you, but for the member here reading this for schooling that just started, this may help avoid such a mistake.