How long does the Army enlistment process take?

Enlistment is fairly easy - couple of weeks and usually that is getting into MEPS and then transport to his training school slot. Schools have certain start dates and the Army also has to do a background check. The background won't hold him up getting into the basic training but may hold him back from starting his advanced school slot until he gets his background done or for some schools a higher clearance type.
Here's a link for you and him to check out.
https://www.todaysmilitary.com/how-to-join/enlisting-military

It depends entirely on if he has any medical conditions, if the job he wants is open, and if there is a slot at MEPS for an appointment. It can be as short as one month... Or ten or more (it took me about 10 months)

Don't bring any documents aside from a photo ID when you first visit a recruiter. Keep it light. Discuss jobs and the army as a whole. Find out as much as you can... Then start talking paperwork.

Instead of worrying about documents... Look up MOSs... Make a list (or if you're set on one... Stick to that one) it's important to know what job you want because recruiters have a limited knowledge of the various jobs the army has... So do your own research and guide your own decision, the recruiter will try to sell you any job that's open... That's their job.

Best of luck!

Depends really on how old the person is, how much of a life they have lived, where they have lived, what they have done etc. The younger a person, the less time it takes.

Basically works this way. Goes to a recruiter and they talk. Could take a few hours. Then the recruit is setup to take the ASVAB. If they have not already ie in high school. If they have not then they are setup to go to MEPS and take the test with a group of others that have not. The test only takes a bit to score so they are likely back at MEPS the following weekend to begin the screening. PRIOR to this they have sat down with the recruiter and filled out their enlistment forms.

MEPS is usually a two day process and at the end of it they are sworn in. This is the initial swearing in. They will go home with a ship date for basic. When that day arrives they will return to MEPs and swear in again.

This process can take as little as 2 weeks.

ma'am, it depends on the applicant and what they want. I can get an applicant in the door Monday and have them enlist the following Monday. (the only reason I cant do it any sooner is because I have to wait on fingerprints to come back.) If he has no law violations or medial issues its easy.
bring, at minimum: Drivers License or I.D., SS Card, Birth Certificate, High School Diploma, college transcripts if he has them. (if he is married a marriage certification. if he has children he needs their ss cards and BC as well and the ss card of his spouse)
he will need the information for all of his immediate family members (to include DOB/Phone/Address). employment history for the last 10 years (or go back to age 16) to include a supervisors name/address/phone number.
he will need, at minimum, three non family references (for a security clearance)
if he does have medical issues, he will need all of the doctors treatment notes from the issue and a letter releasing him from the doctors care stating he is fit for military duty.

make sure he meets ht/wt too!
:-)

Taking the above example (Monday to Monday) he can enlist and still choose a "ship date" that best fits his and your needs. let me know if you have any additional questions or if I answered everything. good luck ( [login to see] )

Mine was one week

Thanks, everyone. Your answers were very helpful. He's 23yo, no medical or legal issues, physically fit and well within H/W. He plans to visit a recruiter this week, but wants to enter DEP until after the first of the year. His goal is Ranger Regiment.