Let me preface by stating that everything depends on the laws and policies of the BON in the State where you live and practice. So if you have access to legal council you might seek out advice relative to your specific situation. Be careful about "volunteering" for any program offered to you by you state board unless you fully understand what you are getting into.
State Boards of Nursing in general operate under the mandate of ensuring that nurses are safe to practice. One of the things they look at is your ability to make safe sound judgements. Driving under the influence is not a sign of safe sound judgement. The best policy is to never drive even after just one drink. Many nurses who are not alcoholics end up in monitoring programs simply because they lacked the judgment with regard to drinking and driving.
Also be aware that in the aftermath of the recent tragedy on Taconic Parkway where 8 people including 4 small children died in an alcohol related crash states are craking down on DUI's - In California there is a bill to permanently revoke a driver's license after a 2nd DUI.
Whatever you decide - be safe out there - and if you think you may have a drinking problem please do something about it.
Peace and Namaste
Hppy