This question is closely related to this Accept PIP or resign? question, but is slightly different.
I am a victim of a conspiracy by my supervisor. He has been hatching a plot against me for the last six months behind my back and I have been informed very recently of the consequences. Now I know that I will be asked to sign a PIP within the next few days. The duration of the PIP will be 30 days. (The PIP has got nothing to do with my performance: the supervisor is doing this because of personal grudge against me).
Which of the following courses of action will cause the least problems for my career over the long term (5 years or more) and why?
Resign from the company even before my supervisor or a HR person brings up the PIP, with a notice period of 30 days.
As soon as my supervisor or a HR person brings up the PIP refuse to sign it and resign immediately with a notice period of 30 days.
Sign the PIP, then resign (with no notice period) shortly before the PIP period ends.
The usual courtesy notice period is 2 weeks. Since this is an "at will" employment, there is no legal obligation to give any advance notice.
My apprehension is that my 30 days' notice may be abused by terminating me before the end of the notice date. Since this is an at-will employment, the employer can terminate me before I planned to leave the company.