You must become a US citizen in order to petition for your parents. It will take three years from becoming a permenent resident before you can apply for citizenship if you stay married.
I agree with my colleague. You and your fiance should schedule an appointment with an immigration attorney in your area familiar with cases involving military members.
I understand from your question you do not have legal status in the US. First you have to become a lawful permanent resident, then you need to obtain your citizenship. Once you become a citizen, then you can sponsor your parents for their permanent residency.
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There are different requirements as to who can petition for alien parents. Once you are married, your age is not the relevant factor. In order to petition for your alien parents after marriage you will need to, as my colleagues have already mentioned, be a United States Citizen. If you do not already have a Legal Permanent Residence card ("Green Card"), you will need to obtain one through your spouse, and then maintain it for 5 years before you are eligible to apply for United States Citizenship.
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