Greetings,
I've never heard of 1000 mg percocet. But if you took one pill five days ago I'm sure it's out of your system. If you need to know the half life, of any drug just type in percocet in a search engine and you can find out who made the drug and all about it.
If you have to take UA's for workmen's comp you should probably only take drugs that are prescribed. I know it's hard, but for most of us here that are on pain managment have learned that you screw yourself up big time with the doctors if you take meds that aren't prescribed.
Hope this helps and you get better
V