When you start experimenting with different types of enamels (read: fingernail polish) to decorate your batteries.
(Bonus points if you have deadlines you'll "get to in a minute" while you "experiment")
You followers and friends on Twitter start referring THEIR friends to you when they have questions on eCigs/Vaping
(Bonus points if one of your followers says to another in a conversation "Doesn't So-and-so always talk about some eCig company?" Bonus points +1 if you convert the query to a sale/new follower)