There's been a lot of confusion about the schedule for these two events, so I'm going to quickly outline the schedule for everyone:
Each event will appear randomly between 6-12 days on a weekday.
When they appear, they will do so at 11:00 UTC and run for 24 hours.
Each event is on its own schedule, one does not take the place of or precedence over the other. However they won't run on the same day unless its a special occasion.
So this means if, for example, you see Credit Heist on a Monday, it has no bearing on when Droid Smuggling will run and vice versa. Its not one or the other, you get both on their own independent schedules. Hope this clears that up!