Monday morning.
The owner opens the churn dashboard: eleven cancellations last week, seven of them in the second month of the mid tier, five citing the same reason from the cancellation form.
Trials started last week number forty-three; fourteen have converted and the rest will receive the day-six reminder tonight.
A member on the top tier whose annual renewal failed on Saturday is in the retry column: the first retry is tomorrow, the first dunning email went out in the owner's wording, and access continues through the grace period, so there is no Monday-morning complaint.