I paid for a purchase in 2017 but arrived in 2018. Can I deduct it in 2017?

I’m a musician, and in December 2017, I ordered and paid for a musical instrument from Germany. Shipping took a long time, and It didn’t arrive until 2018. Am I able to deduct the purchase in 2017 or do I need to wait until it’s actually put into use, which would mean 2018?