you are skipping the most important step!
the first step of proving that bitcoin is indeed in a bubble and then start speculating about when it is going to burst. you are just assuming it already is in a bubble and then you are asking about when it will burst!

so first things first. is bitcoin in a bubble?
the best answer that i can give you is a "Maybe" and you can not be certain of it until price really drops, and drops big like 50% or more and also stays down not just come back up immediately like with every FUD dump