There's no single, universally applicable answer to the minimum Time-In-Service (TIS) requirement for promotion from Staff Sergeant (SSG) to Sergeant First Class (SFC) in the military. The requirements vary significantly depending on the branch of service (Army, Navy, Air Force, Marines, Space Force, Coast Guard) and even within those branches, sometimes depending on the specific Military Occupational Specialty (MOS) or rating.
To find the precise minimum TIS requirement, you must consult the specific promotion regulations and guidance for the branch and MOS in question. These regulations are usually available on the service's official website, often within the personnel or promotion sections. You should also consult with your supervisor or a military personnel specialist.