I am going to methadone clinic tommorrow and get them to convert me over from suboxone to methadone can you do that in one day?

No: You need to do this under the care of a doctor who can determine when it is safe to start suboxone. Someone taking Methadone will go into severe opioid withdrawal if given Suboxone too soon. One recommended way to transfer from Methadone to Suboxone is to taper down on Methadone to 30-40 mg per day, stop Methadone for 2-3 days, then start Suboxone once withdrawal symptoms are severe enough.

Yes, but....: You can be dosed with Methadone the day after you were given Suboxone but remember, Suboxone blocks all other opiates/narcotics and makes them ineffective if its still in your system. For most people, Suboxone remains in their system for 3-5 days. Thus, if you are given Methadone the day after, it just won't be effective, but it won't put you in withdrawal.