Hey There! I researched federal employment for years prior to applying because they had the best retirement & disability retirement plans available. The government only requires 5 years of federal service to be eligible for disability retirement. I worked for as long as I could until my body couldn't handle the workload or stress and retired.
The process took about 6 months after I applied and my payments began at the beginning of the new year. I actually do consult as a paid hobby- helping individuals with disabilities become eligible for federal employment since there isn't a conflict of interest anymore for me.
I worked as hard as I could to move up as fast as I could because I never knew when my body would give out. I also saved about 20% of my income through my TSP(the government's ira program) every year for the 8 years that I worked.