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?
If you really wanted to buy a bunch of bitcoins make sure that you wait for the dip, but the problem is no one knows when will the dip will occur on the market and on every coin in the market, that is unpredictable you just have to stay connected to some sites that are tracking the movement of bitcoin in the market, and from there you will be more knowledgeable and updated on the latest happenings of bitcoin so that you will know when is the right and good time to buy.