Ah...the 20-day consideration is a rule in place for those that present an email or copy of the letter. If you have the original, it’s usually 30 days.
Of you have visa exempt stamp, bring the consul letter, 2 copies of TM-7 with picture, TM-6 departure card, passport page, and current entry stamp to airport tent area and they will help you out. If you have Non-o, go talk to the desk officer.
You need to have at least 21 days on your current tourist visa to apply for the retirement Non-O. You will need to cancel your visa (extension of stay), apply for 7-day emergency extension, get consul letter or supply affidavit as to why you can’t get one, apply
For a 30-day tourist visa extension, then drop Non-O Retirement application. Whew.