How long until this suboxone makes me feel better? (methadone before hand)

Might be 2 days: Methadone last very long in your body, so Suboxone will put you into immediate withdrawal symptoms, that might last couple of days.

Methadone->Suboxone: Transitioning from Methadone to Suboxone can be challenging but possible with the right planning on the part of the physician and the patient. It is not advised to jump into Suboxone from methadone. Frequent dose adjustment is often needed. Precipitated withdrawals are not fun for he patient or the treater. In certain cases can take up to a week for a successful transition/induction.