I tried to search for any occurrence of "17 days" in all the PDFs of Buk-related stuff I have, and found four instances of him using those magic words, but none of them had anything to do with his modus operandi.
As far as I know, he hoarded the manuscripts (check John Martin's impressions on his visit to Bukowski's place, when he saw a closet full of poems) and never bothered to check them once a morning after drunken night of writing had passed.
On a totally unrelated note: Bukowski had spent 17 days in Moyamensing prison.