Originally, when bitcoin declined from $30's to $2's, I really wasn't ready to start pouring money into it as the dropping seemed to be never ending.
Yeah, it is easy to say now, you didn't buy bitcoin at $2.00. Well, at that time you probably wouldn't either.
I decided at that time I would wait for a stable long term price to put my money in. My idea was that if the price would hold stable for at least a year and showed no signs of dropping, that was the best time to invest. This way you limit your losses.
Well, I purposely stopped watching bitcoin for a couple of years, because it was a waste of time to me to speculate. I then lost interest in it and didn't think much about bitcoin.
However, when the price rose to $1000, I was looking at the bitcoin price chart. It was clear that the best time to have bought bitcoin would have been around $10-13. This was a stable long term price where you could buy in and minimize your losses with possible sustainable growth.
So the question is, when should you buy in now?
If you want to minimize losses the best time to buy in is after the price is stable long term, like a year. This may be in the $20-$100 range in my opinion. But what ever it is, you're better off waiting for the price to stabilize long term.
Try and control urges to buy in at the bottom or trying to time your buys.