Structural changes needed for program accessibility must be made as expeditiously as possible, and should have been made by January 26, 1995. A public entity that employs 50 or more persons must have developed a transition plan by July 26, 1992, setting forth the steps necessary to complete such changes.

For additional information, take a look at the following resource:

FAQ: What changes must a public entity make to its existing facilities to make them accessible? [2]