How do I get a security clearance?

Speak to your security manager

Depending how old the DUI is you may not be granted a clearance for up to 7 years. It depends on the state and how the courts report. You can write to the court that you received your conviction in. You must explain that you are now in the military and this is affecting your career. Make sure to say something about how you have matured since the incident and you have learned your lesson. Some courts will reduce it to a reckless/careless driving and not a DUI especially after you have already paid your fines and completed court requirements. Be patient, talk to your chain of command and also your unit security manager.

This is one of the things that has always puzzled me about security clearances. A young American stubs his toe while in his teens. Granted a DUI reflects a lack of maturity. But think about all the people in the military who have clearances because they did not get caught. But you take a person who was born in a foreign country who has a skill that Uncle Sam needs and wallah, instant clearance. Of course they say they have conducted a background check on that individual but how much information can be gathered on someone born in a foreign country. Personally, I feel that someone who was arrested on a misdemeanor charge should be able to get a clearance if he/she had not been in trouble since it happened. I know that during my military career I lost many knowledgeable soldiers because they could not get a clearance because of something that happened in their teen years, like a DUI or fist fight.

I am not sure what current protocol is with recruiters is in regards to getting Soldiers clearances. Maybe one with some more knowledge could chime in. I was in a similar situation entering BCT however there was never a clearance investigation conducted. I told them about my charge (DWAI) and they said your not getting a clearance, pick an MOS that doesn't need one. If you have to go through a reinvestigation. All you can do is be honest. They are going to find out anyway. Identify the issue, as well as what you did to rectify the situation. (Counseling etc.) Pay special attention to exactly how the question is asked during the investigation. (The questions regarding substance abuse typically begin with "Have you EVER"). Have fun at the CEHC shcools when you get there.

SGT (Join to see) Your investigation from 2013 is still valid, you can request for a new determination to be made if you are going somewhere that you will need that clearance (school, duty station for example)

18 and a DUI. You shouldn't even been allowed in and especially into a MOS that requires a security clearance.

I would like to know what is a related MOS SCHOOL FOR A 12B?

What schools?? PLDC, BNOC??

Your commander, ask for a form that is used to apply for training and records.

BLUF - it comes down to need.
If your unit doesn't see a need for you to have a clearance, they won't submit you for one. Just one DUI will not stop adjudication of a clearance. lots of other factors will: non-payment of debts, several alcohol or drug involved incidents.
BTW: I don't understand why you would have been submitted for a clearance pre-basic, especially since no clearance is required for 12Bs.