Depends on the route, but at least a few years while you complete (or get close enough to) a bachelor’s degree. I’d say it depends on whether you’re active or reserve, whether by an officer you mean W-grade or O-grade and on which of the four officer programs if you mean O-grade.
Generally speaking, if you’re on active duty, either the military will send you to college, or you’ll finish it on your own. If the military sends you through some commissioning program like ROTC, awesome. But then you owe some years after that.
If you finish a four-year college degree yourself, it’ll cost you money and sleep, and you’ll still need to complete the equivalent of OCS.
Whether active or reserve
I’ll presume that you’re starting from basic and not entering the military (as some do) later in life and with an advanced degree, but who just want to do their time. I’ve known of Soldiers in the Army (for example) with law degrees, medical degrees, other doctorate-level certification, who said, “Forget all that. I want to be a Private (E-1).” Oh, they exist.
If you just graduated high school and have successfully entered the military at Private (E-1), then congratulations. You made it. If you’re on active duty, good luck. It’ll be difficult but not impossible to complete a four-year degree while juggling your workload.
I did so as an active duty U.S. Marine, enlisted, Sergeant (E-5). I don’t believe I could’ve finished without stopping while as a junior enlisted Marine.
If you’re in the reserves, I think you’d have an easier time. But that depends on what you’re doing when you’re not drilling or conducting annual training (AT).
There exist four types of commissioning programs, which I’ll get to below. One type is a direct commission, which usually means doctors or lawyers. Direct commission means no equivalent of boot camp to commission. In the Army Reserves and Guard, one can direct commission from enlisted to officer without being a doctor or lawyer.
Whether W-grade or O-grade
There exists a high school to flight school program, that will, if you succeed, bring you into the Army as a Warrant Officer (W-1) and a helicopter pilot. I think it sounds awesome.
But if you’re already an E-1, it’ll take some years to go Warrant Officer, and it depends on the job. Most military jobs require between 4 years to 8 years to go Warrant. I knew a Specialist (E-4) who got accepted into flight school on his second application, and he was only in year three of his military career.
If you mean O-1/O-1E (Second Lieutenant or Ensign), it’ll take a few years. Depending on current policy and the commissioning program, you don’t have to have a bachelor’s degree. You can commission with an associate degree, but with those programs, the rule is that you must soon finish a bachelor’s degree.
Four commissioning programs
There exist many different names and different programs, and they vary per branch. Generally, there exist four categories of commissioning programs: direct commission, Reserve Officer Training Corps (ROTC), Officer Candidate School (OCS), and the five service academies (West Point, Annapolis, Colorado Springs, New London, and Kings Point).
Usually for doctors or lawyers, but open to other jobs in the Reserves or Guard. There have also existed (although very rare) battlefield commissions, where enlisted members have been commissioned on the spot.
Many four-year colleges offer the program. You’re probably better off attending ROTC before joining the military.
If you just arrived at your unit and serve on active duty, your unit will seem reluctant to release you to attend an ROTC program, such as Green to Gold in the Army, but it could be an option. By the way, once there, you could possibly ride ROTC out through a master’s degree.
I remember that the Marine Corps had a few programs available to active duty Marines, such as MECEP, which serve as the equivalent of ROTC programs. The Marine Corps makes it tougher for Marines to commission than for civilians off the street. Why? Don’t know. So I commissioned into the Army. I get paid the same.
This is the route I took. The Air Force calls it Officer Training School (OTS). You typically already need at least a bachelor’s degree to attend. It’s officer boot camp.
There exist five of them. You can attend any academy to commission into any service branch, but typically each academy leads into one branch; e.g., West Point into the Army.
If you’re already an E-1, you’ll need to jump through hoops to attend, and probably even more so than you had applied as a civilian.
I hope that answers your question. Good luck, brother.