If I have money now, I would buy half of bitcoin because in next three months it will double the current price. This is real because it always occur this way after 5 years remember in 2011 and 2017 from the market charts and caps. And this year will break more even.
Buying cheap is the best formula. But what is cheap? I would say that buying right is the best formula. Your formula may work for you, but I do not think it is universally applicable. As it comes with a lot of anxiety. Besides, your idea of bitcoin's price is just a speculative as it is with every other person. Do not mount so much pressure on yourself because of FOMO. I don't know how long you have been in the market but if you have been here long enough you would have heard about Dollar Cost Average strategy which is actually the best out there. You should read up on it.