I want to request to the Army Board of Military Records to remove a letter of reprimand that I received. How long do they

Depending on whether you are active duty or not will determine with which board you should file your request. Active - DASEB; not active - ABCMR. From the time the board receives your request, it could take up to 12 months for the board to consider your request. You are not required to have an attorney to file a request with either board. However, an attorney would likely be able to prepare a more persuasive request along with better developed supporting documentation.

Before making a submission you should gather support for your package. In particular you should determine if the GOMOR issuer is willing to support you. Depending on the type of "misconduct" it can take from 9-18 months. A lawyer experience with the boards can help you prepare a better and perhaps more focussed package. A simple letter from you doesn't work.

As a preliminary matter, you need to know that the GOMOR has to remain in your OMPF for 1 year before you can make application to remove the GOMOR from your OMPF. Your first application must go to the DASEB and if you lose there, then you apply to the ABCMR. You can make the application on your own, but with so few opportunities for relief and so much at stake, you should seriously consider hiring experienced counsel.