Hey Bradley, Welcome to BiggerPockets and thank you for your service! My husband is in the military as well :-)
Making the decision to become a real estate agent is definitely not something that should be taken lightly. As others have said I agree that joining a team right off the bat is a great way to get started because it can be extremely overwhelming at first. Burnout in this field is real so it's good to have a support system. I made the mistake of going solo in the beginning and wish I had joined a team sooner. A lot of companies have great training as well, some not so much, so I would definitely interview different brokerages before committing to one. As far as money goes, start up costs aren't too much- a couple thousand at most. NH has a required 40-hour pre-licensing course (now offered via Zoom since COVID), so if you become an agent in CA first and want to jump right into it when you move to NH I would definitely try to knock that out beforehand! Licenses have to be renewed every 2 years so if you leave CA after 2 years you could just go inactive if you do get licensed there first. I think becoming an agent is a great idea if you're planning on investing especially. Getting the commissions from your investment properties is a huge plus.
Feel free to reach out if you have any more questions!