When do I deduct the business expense for an event? When I pay for it, or when I attend it?

I am a sole member PLLC.  I attended an event over the weekend out of state (hotel, meals, mileage, and the cost of the event itself).  

I PAID for the event on 1/26 but attended on 4/13.  The travel, meals, lodging all billed out on 4/13 and 4/14 (hotel was refundable, so didn't bill to my company card until 4/14)  All expenses were on the company credit card.