How do you start a cog invasion in tontown

You have to defeat the C.J. then you get special rewards to summon 3 types of summons one is to summon a cog the other is to summon a cog building and last is to summon a cog invasion These can be located by looking at the Cog Gallery in your Schticker Book. Just click what ever cog you want and it will eather (depending on what you pick) fly down on the street start invading or a building of its type (bb lb cb sb) will fall on the building in front of you