6 months to 2 years
you have to fill out form DD293. Additionally, you must prove through documentation your separation, characterization of service or narrative reason was/were either inequitable or improper. Few upgrades are given by the Navy Discharge Review Board (NDRB) for Navy and Marines. The Army DRB is much the same. The Air Force DRB tends to view passage of time a bit more favorably than the other services where passage of time is irrellevant. Well documented Post-service conduct usually helps an applicant's case if they can show their in service misconduct was an aberration, and not indicative of their overall character. An applicant is entitled to a document review and a personal appearance hearing before the DRB within 15 years of the discharge date. If the personal appearance is elected first, the document review is waved. Applicants should always have representation, and should always elect the document review first in order to allow for adjustments etc if they are unsuccessful. Then, they may re-attack in a personal appearance hearing.
There is no general timeset. You have up to 15 years to file to the board of appeals to upgrade your discharge characterization. Generally the rule is six (6) months. So long theres not any punitive action discharges (BCD, DD) then your discharge from Under Honorable to Honorable is usually granted. That period can take a few months up to a year. So try to be patient. A great way to start is at your local VFW post, you will need to complete DD293 found here..(See relaed Link) just copy and paste the domain in your browser. This needs to be mailed to your respective military review board. (army, navy, af,) I believe are the only three (marines, and coast guard are through the department of the navy if I recall properly) You may be required to make a personnel appearence in DC so be prepared for that, or your legal representation. There are resources out there dont fall victim to the myth that "it automatically upgrades", or "its impossibile to get the upgrade" thats bull! Most who complete the leg work (unless its a punitive discharge) get it.The above answer is incorrect with regard to Navy and Marines. The Navy Discharge Review Board (NDRB) rarely grants upgrades to characterization unless clear inequity or impropriety is proven. The NDRB presumes regularity in the conduct of governmental affairs, and the burden is on the applicant to prove inequity or impropriety. Upgrades do happen, but the applicant normally needs to provide a well documented argument backed up with documentation. I was a member of the NDRB for three years, and adjudicated thousands of cases. There is assistance available including free assistance from the American Legion. There is also a facebook page that is very good you may want to check out regarding military discharge reviews.Applicants are entitled to two reviews before the NDRB, Army or Air Force DRB's within 15 years following their discharge date, a document review, and a personal appearance before the board. Applicant's should always elect to go to the document review first. If the personal appearance hearing is elected, the document review is waived. I highly recommend seeking competent assistance in order for applicant's to put together the best application possible.