Although I'm not sure that the increase of value is linear, the calculation is quite feasible. What I personally doubt massively is that the bitcoin infrastructure - which consumes already as much power as a nuclear power plant is able to produce - can cope which such an increase of adoption. More adoption is IMHO a big threat to bitcoin, since there is already a lag of several hours for transaction during a high-traffic period like during the last big value explosion.
What I do not doubt is that the best time to buy is most likely now.

Just mentioning, I'm not an expert in this regards, so this is not an advice or a recommendation, just a personal opinion. Do your own research or ask a real expert or do both. Or just work hard (rofl) or whatever... ;)