Hi Kthames, I think this is a complicated question and the answer depends on a number of factors. Are you in a union? If so, seeking advice from a union lawyer who knows your state statutes and employer's history with other workers is important. It is important to let your employer know about a disability before your performance is affected and judged in an evaluation. However, before you meet with anyone in Personnel, it is also important that you have thought out what specific accommodations you will require (working flextime, reduced responsibilities, rest break during the day, working from home, etc). Your employer will have to make accommodations for you. But do get advice before telling, as all employers will not deal fairly with people who have disabilities. If you don't have a union, it might be worth seeing an employment lawyer for a one-hour consultation about the best way to do it based on your state laws and the specifics of your employment contract. Good luck!