Depending on how long you've been on them, the physical withdrawals last about a week or so with day 2-4 being the toughest (at least in my opinion). If you haven't taken them too long, you shouldn't have anything to worry about.
Is there any harm in cold turkey off of percocet? No, generally not at all. Its not fun, but opiate detox will not kill you. **If you have any medical conditions like heart issues or blood pressure issues etc you should really talk to your doctor.**
Generally though, cold turkey off of opiates is safe, but miserable.