How much time do we have left until its becomes proper main strain?
Can someone tell me where we are on this chart please?
No one can answer that question and any answer you might get will not be precise one.
we are still in early adopters phase but I don't think bitcoin price will follow that line chart you have. Bitcoin price is not only accelerated by hype/speculation there is real demand for bitcoin so we can expect a gradual straight upward line for bitcoin.
$4k is good entry point, good luck with your investments.