Once you pick a start date, every step is locked to hours, not vibes. A 7-day CIDR will put a pull and a shot on whatever weekday the maths says. That is correct biology. It is also how you discover the only person who can do CIDRs is at a wedding.
HerdMate dates the run from one start. Look at the calendar before you enrol 80 cows. If a critical step is Saturday, you still can start — you just staff it. A warning on weekend steps is on the build list. Until then, your eyes on the calendar are the warning.