As an amateur comic artist/writer, can I write off comics reference books on my taxes?

I’ve been amassing quite the collection of reference books as I work to break into the comics industry (freelance), but if I haven’t made any money from it yet, can I still write off the books and supplies, etc? And do they have to be bought the same year for which I’m filing taxes, even though I bought them with the intent to use them for my freelancing?