You should plan ahead to file your petition and now when exactly you are eligible to file. As far as timing is concerned an applicant for naturalization must meet certain continuous residency requirements. A petition for naturalization can be filed up to 3 months before the applicant meets the continuous residency requirements.

Once you have determined the appropriate time to file the petition, the next step is to gather the required documentation. The most common reason for delay or rejection of naturalization petitions is failure of the applicant to provide the required supporting documentation. In the case of a naturalization petition, little supporting documentation is required. You will need:

1. A photocopy of your lawful permanent resident card (front and back.); and
2. Two color photographs of the applicant.

Be sure to keep copies of all documents sent to the USCIS for your records.