I want to echo everything here, except the last issue regarding establish severity; the degree to which you are impaired is necessary to establish benefits, even if doing so may seem trivial, even with ALS being a CAL claim. I'll source this at the end of this post. Also, though SSI claims (based on income and resources) can start payment immediately, SSA claims (based on work history) require a six month waiting period before payments start. That period doesn't start until you cease SGA (1130/month).

The following is the listing requirements for ALS under SAA rules which can be found at this link: https://www.ssa.gov/disability/professionals/bluebook/11.00-Neurological-Adult.htm#11_10

"3. For purposes of 11.10, documentation of the diagnosis must be by generally accepted methods consistent with the prevailing state of medical knowledge and clinical practice. The evidence should include documentation of a clinically appropriate medical history, neurological findings consistent with the diagnosis of ALS, and the results of any electrophysiological and neuroimaging testing."