12 hours is about long enough to begin to feel the effects of withdraw. Begin is the operative word... it will get slightly worse before it gets better. 40mg of oxy is a decent amount, and a fast taper never really works to get around wds. The fear that you will create symptoms is a symptom: anxiety. As for the physical, what you have been told is true... aches, the runs, insomnia, sweats, etc... they do happen. I noticed in your earlier posts that you can't go to a Doctor for help. So, use the Thomas recipe... and drink lots and lots of fluids, take vitamins, and do something with your mind and your body.
You can expect the wds to peak at between 48-72 hours, so be prepared. For me, day 3 is the hardest. For some it's day 2, for others day 4... others experience awful days at day 15, or even more than a month later. It depends on the person, and that is why you need to figure this out: Am I an addict? Either way, yes or no, you need a support group. Find people to talk to. Good luck!
Eh other than my calves being sore, i feel ok. I bought motrin, tylenol pm and immodium as suggested by others. I think my other symptons im having now may actually just me feeling "normal", aka the small aches and pains were covered up by the pills for a month. I will keep you posted, as 2 or 3 asked me to!