Look back to when your first audit ended. If it ended Nov 1, 2016 then your window for unannounced could be between Oct 1 and Dec 1. If you 2018 audit was Nov 30, it still can't be past Dec 1.
"4.7 Unannounced Re-certification Audit
Within three (3) certification cycles the certification body shall conduct one (1) unannounced re-certification audit of the site. The unannounced food safety audit shall occur within the sixty (60) day re-certification window (i.e., the anniversary date of the initial certification audit +/- thirty (30) days). SQF sites shall be required to undertake one (1) unannounced audit within the three (3) year certification cycle.
i. The site’s certification cycle begins with the initial certification audit date. Unannounced re-certification audits shall occur once in every three (3) certification cycles."