How long does it take for me to get a green card or what are my options since my student visa will expire soon?

Your question is less than clear, since you stated: you and your wife already are Permanent Residents; although she is your wife you plan to become married in a few months; and you now have a student visa. In order to petition for a spouse to adjust status in the U.S., generally (1) the petitioning spouse must be a U.S. citizen, in which case an Immediate Relative case with immediate availability of a visa can be filed, and eligibility still can be maintained notwithstanding the beneficiary spouse's failure to remain in lawful status; or (2) the petitioning spouse may be a Lawful Permanent Resident in which case there is a delay for visa availability and the foreign national spouse must be in valid nonimmigrant status (such as valid F-1 student visa status) in order to adjust status within the U.S. Significantly more information would be needed in order to advise about immigration eligibilities, options and strategies. It would be wise for you and your wife (or fiancee) to consult with an immigration attorney who, after learning all of the relevant information about each of you, would be able to provide advice and offer legal representation in the often complex immigration application process.