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?
The best time to buy is when the value of bitcoin is low than usual or the down trends is consistent. Definitely, you must buy some bitcoin so that you will earn money when the value increases. You must understand how the market works by studying it on many sources of information. Kindly read some of the forums here for those sources.