I bought a bunch BTC when it was $17000, then bought a bunch when it is $14000...then the price dropped until 2 days ago. I bought a bunch again when it was 6000ish...haha, now the price went up...so, really, when is it a good time to buy? When it dropped for a while and it rose a little bit, then drop again, then buy?
I'd argue the answer is that it's ALWAYS a good time to buy, depending on how long you plan on holding.
If you're a medium-long term HODLer then you shouldn't worry about short term price movements as the market is so incredibly unpredictable, BUT if you're looking for a short term flip then a good way to play that is wait for a dip of 10% or more, then HODL until the market swings again.