When you just post a message, if you look at how long ago it was posted it will always say “1 minute” whether you look at it 10 seconds or 45 seconds after the publication.
I suggest to have a display in seconds for the first minute to know more exactly how long ago the message was made. It’s not necessary for it to be in real time, but that it only being updated when you get on the page or when you reload it, a bit like on Youtube.