You'd generally claim the expenses in the year paid, so if you paid the expenses for all 23 comic books in 2017, you should claim them for that tax year.

If you use a Cash Method of Accounting, which is used by most people with individual income tax returns, you'd claim the expenses when you paid them.  If you use the Accrual Method, you pay when you incurred them, as opposed to when you paid them (this may be the same tax year.)