What can I expect being 16 days off methadone (after 7 yrs) and 1st day of suboxone?

May be withdrawal. You might experience some opioid withdrawal effects such as sweating, headaches etc. It depends on the dose of Methadone you were on too.
A very good day! You probaby will not have any problem. The Methadone after 16 days is almost entirely out of your system. Any craving for opioids will be handled by suboxone within one hour of starting this safe medication. Normally Methadone is a challenge when starting suboxone, because of its long staying power in the patient, but after 16 days, you should be a star. Great way to deal head on addiction!
CONGRATS!! You should be alright with over 2 weeks of being off Methadone but it will depend on high the dose was that you stopped. Hopefully you tapered and so it should be really smooth. Stick with the program. It works and should be better than with the methadone.