@barad my solution for this is to use Date/Time based triggers. Here’s some documentation:
https://help.manychat.com/hc/en-us/articles/14281170185628-How-to-set-custom-rules-with-Triggers-Conditions-and-Actions
I setup a datetime user field with the specific date and time I want the message to be sent, and then I use that user field to trigger the flow that sends the message that I want.
With this setup I can get better control of when exactly to send the message.
As for the smart delay, let’s say you have a 1 minute smart delay, and have it setup between 21 and 22:00.
If the person enters the smart delay anytime before 22:00 (today) to 20:59 (tomorrow), it will send exactly at 21:00 (tomorrow).
If the person enters the smart delay between 21:00 and 21:58, then it will wait 1 minute and then send the message.
So if a person enters at 20:48, they’ll get the message at 20:49.
Hope this helps ;)