I'd suggest dollar cost averaging.

You can't predict for certain when exactly bitcoin prices will bottom or when it'll top out. What is somewhat certain is that we're likely going to experience a bull market of some sort this year, and the overall trend and sentiment is much more optimistic than what it was just last year as well as 2018.

I think that $6k is the definitive bottom for this bear market in any case, so with the current dip, you might as well load up a little. That is, provided you are willing to hold for the long run and hold through dips. Otherwise, there is no point.