I did something similar. I encouraged members in my YGs to create an IO login and look around. Many found IO groups that were of interest to them and joined them. That is really ideal as existing, active IO groups give new IO registrants a richer experience.?
There is more advice on the wiki for group members. You don't have to be a member of GMF or log into Groups.io to read it. /g/GroupManagersForum/wiki/home