Whether 1 hour or 24 hours, your employer would be extremely inconsiderate not to give you time off to attend the oath ceremony, even if it means you taking the time without pay.
AFAIK, it'll be on a weekday. I don't think IRCC staff conduct ceremonies in the weekends.
I recall reading that IRCC requesting applicants to clear their schedule for about 3 hours for the entire process but don't quote me on that. I am not very sure, I'm just vaguely recalling.
I'll let someone who attended virtual citizenship ceremony respond to this question.