Can i change my primary MOS before i leave for basic training?

You can change it but they only allow so many people in a month for each MOS which means that you might have to wait longer or might go sooner. But be sure that your recruiter cant stop you from changing it i changed mine a total of three times before i left. Its just more paper work for the recruiter. If you need any more help you can email me. And you can change it up to the day that you actually leave for boot camp and you will realize that when you go to MEPS again on that morning of your flight to boot. You will have to redue your entire contract again and swear in again.