It took me more than a year of constant (weekly) highly intelligent exposure to bitcoin, before I bought any. It took an additional year and more, before I allocated a significant % of my holdings to it. I even knew of Bitcoin before Mt.Gox opened, and that was purely theoretical and did not interest me.

So expect a large percent of the ones who heard in early 2013, to buy in with significant money in 2015-2016. Unless they are slower to understand than I was, in which case it takes even longer.

What I see is a very rapid growth. Today is only 5th of May, after all. I'd say hundreds of people understand it in May, and millions in June. In July it is too late to buy bitcoins for investment probably.