When is a right time to start monetizing a web app?
I am starting a family of web apps which are supposed to be really easy to use tools for freelancers and small businesses. Project Bubble (http://www.projectbubble.com) and Invoice Bubble (http://www.invoicebubble.com - it's younger brother which is hasn't been launched yet).
At the moment Project Bubble is free, and has been since it launched in November. It's getting a lot of great reviews, probably mostly because it's very fluid in its development and I'm constantly bringing out cool updates. It's also very popular because it's free.
Obviously I can't keep it this way because I want to introduce SSL, Trustee certification, and work full time for the business. I want to launch a monthly billing plan for premium use but I'm not sure how to charge (though I have some ideas such as limiting the amount of projects). Most importantly though, I'm not sure when to charge.
A friend of mine who is an entrepreneur from DC (and avid HN reader) suggests that I just start charging now, even though my 'power users' are only about 10% of the nearly 3000 users that I have, and they are the ones bringing the buzz in. If I start charging that 10% will they carry on raving on about how great the product is? If they don't then I lose a lot of my marketing.
Any advice would be appreciated.
Thank you
Stu @stulogy