Just said goodbye to three of my oldest neighbourinos

At the start of a new event, I copy down the names of all my neighbors and whether or not they have the starting point building. Then I check each day as I go on visits, to see if they have caught up. After act 2 starts, I usually start the reaping. I have only one neighbor that I hang on to, because, as with this event, they didn't start collecting until act 2.
Most have started by the weekend after the start of a new event, my guess is they don't regularly visit until then and have to try and play catch up.