different for everyone, after a month of using 400 mg a day, you could easily withdraw so I say a month and you should have the receptor dependence, problem is, it's not just regular opiate withdrawal your contending with, tramadol effects the mu opiate receptor AS WELL as serotonin and norepinephrine so when you stop you will have 3 different withdrawing sicknesses at once instead of the usual one. Some say Tramadol withdrawals can be as bad as oxy or heroin wd due to the complexity of the different chemicals in your brain it effects. sucks all that pain for something so weak.
I had to get some vicodins just so I could sleep tonight and I got some kratom on it's way tomorrow. that always helps me get off