I don't weigh much, drinks a lot of water and metabolizes opiates quicker than others so if I have only taken 3-4 mg of suboxone and the same yesterday than, his opiate usage would be about 85% effective after a 10hr wait but this is in my case, everybody is different. Even little things can make a difference ie, empty or full stomach, diet, etc. Let us know how things go if you should reach a decision.