Are notifications after endorsement/audit typically posted/batched at the first of the month or are they issued as they are completed?
From my reading and own personal experience, the Member Portal will update first and that same evening is when you should receive your CISSP Welcome notification.
I doubt they are batched and distributed monthly. My Welcome email just came in yesterday evening, and others have received theirs on days other than the 1st of the month. The wait time right now is about 9 weeks and 3 days from endorsement submission.
Also note that when they say it takes 6 - 8 weeks to process your endorsement application, that doesn't include weekends and holidays.