Interesting feature. Good that it doesn't keep recommending people ad infinitum. It stops after it thinks the group is big enough.
But don't send it at the time we specify - send it out plus or minus two minutes and some change. There's nothing lamer than saying to yourself "Wow, what a nice email about 'thoughts you had today.' It came at midnight - wow, you sure were up late! Oh wait, it came at 12:00:00. What a douchebag."
Well, there is something lamer: if you are the douchebag.