IRCC lists ceremony as "within 3 months". Scarborough office is closer to the 3 months mark than say Mississauga where they've recently been telling applicants 3-4 weeks according to other threads. My oath is 2.5 months after DM.
Take a read here:
https://www.canadavisa.com/canada-immigration-discussion-board/threads/scarborough-dm-oath.485211/
Note that of late they've been telling people they will or even
have sent the oath invite by email but it has actually been sent by post. I would check ECAS at least once a week until it arrives and call IRCC if they say it's been sent and doesn't turn up for 7-10 days.
It varies from person to person. They didn't even open my passport. Take the boarding passes.