I looked back at your other posts because I knew you asked some questions and I din't have a chance to answer them. Since you have plenty of time till you test you should buy some instant test strips off the net for cheap. You can find them with a search engine or off eBay is another popular place. Off the net they should be under $2 each plus shipping. Next, I like your plan of substitution first then dilution as the back up if observed (this is why you should get the strips). I don't know the rules of oservation or not when it comes to schools. Maybe you can find a student handbook or policy manual and find out. Is it a private university or state university? This might make a difference, I have no idea. Aerobic exercise, soluble fiber (metamucil is my choice), and staying well hydrated but not overdoing it will be your friends for getting clean. Cranberry juice isn't going to do much. People think it helps prevent urniary tract infections by cleaning you out but it has antiseptic properties when it goes through your urinary tract and not cleansing power. Go for it if you like cranberry juice but don't expect any miracles from it.

You know I used to recommend the whizzinator a lot but I have come to the realization that it is just a fancy carrying system. If the person conducts the observation correctly which is watching the flow of urine leave the body and enter the cup (as opposed to over your shoulder or using a mirror or being very casual about it) they will notice it is plastic and not real. But if you think they might casually watch then it will fool people. So just something to consider.

So practice subbing, acquire some clean urine, fake or real, and take it in with you and if you can't pull it off give them you diluted urine. Hell, you may start testing clean a week before the test and can give them your urine. But that's my starting advice.