How long in advance should I start my citizenship paperwork? I have a green card in this moment.
You can submit your naturalization application to U.S. Citizenship and Immigration Services (USCIS) within the 90-days before your 5th anniversary of becoming a permanent resident.
However, if you become a U.S. permanent resident because of your marriage to a U.S. citizen, you don't have to wait five years. You need only to wait three years as long as have been married to and still living with the U.S. citizen for the entire three years. In this case, you may file the naturalization application up to 90 days before the date you first meet the required three-year period of continuous residence.
Thank you for your attention. Best wishes.