How much time in service for promotion to E3 to E4?

To be promoted from E3 to E4 in the U.S. military, service members typically need to have at least 12 months of time in service and 6 months of time in their current rank. However, specific promotion timelines can vary depending on the branch of service and individual performance. Additionally, meeting all other requirements, such as passing a promotion board or completing necessary training, is essential for advancement.