site:uscis.gov “검색어” 로 구글링 하니 금방 보이네요 ^^
https://www.uscis.gov/citizenship/apply-for-citizenship
USCIS Early Filing Calculator
The information in this part ONLY relates to your time as a permanent resident if you file under Section 319(a) and 316(a) of the INA. You MUST meet all other eligibility requirements when you file.
You may file Form N-400, Application for Naturalization, 90 calendar days before you complete your permanent residence requirement if your eligibility for naturalization is based upon being a:
Permanent resident for at least 5 years; or
Permanent resident for at least 3 years if you are married to a US citizen.