My rules are to wait for a bull market and then buy in the dips. I am more long term investor, and I want to check bitcoin price only once a month.

But here are some problems that I have with this approach. How to know if this is a bull market?  Now it looks sporadic so it is hard to say where we are in the cycle. Most sources say it is a bear market, but it looks like it is growing again.

Another problem is even in the bull market, it can fell at any moment. So if you invest long term, you can check the price in half a year and see you lost money.  For example, bitcoin reached 19K by the end of 2017, then it fell. And it was in this parabolic mode since September 2017. It could've fallen in September or October.