I apologize in advance if this is a duplicate request.
Something I liked about Mailchimp was the "only send between X and Y time" feature. It also allowed for this functionality to match the user's local time zone, if their location was known.
This is nice because a user might signup at say 11:00 p.m. their time, but then we could specify if we want our follow-up emails sent during the day (say between 10:00 am - 3:00 pm) moving forward.
At some point this would be a nice add-on to existing campaign functionality (and possibly also for scheduled list blast emails).