I Was Prescribed Percocet For Back Pain. 30 Pills Usually

I was prescribed Percocet for back pain. 30 pills usually last me about 6-8 months. I only use when I have to. Went to get one tonight and bottle is empty. I have some left in an old bottle from 2010. Is it safe to take one of those until I see doctor on Friday. Real question is just on the safety of the medicine