For two bull cycle that's 8 years but to just be in the safer side lets lets do 10 years that's a decade before thinking about cashing out some profits. If you just follow the two bull market rule, you might end up selling in a bear market and although you'll still be making a profits but you would have missed out of potential gains that you would have gotten. Of course no body rejects more money so after you dun invest, try make the period why you want sell make e for be during bull market. Trading Bitcoin isn't even advisable because why you go dey stress yourself dey chase small small profits when you go fit just hodl Bitcoin and make easy profits.
For better clarity, best to keep in range within 8-10 years window, which comprises of two cycles but as we know some times, one market phase may delay to exceed the specified year. Bitcoin investment is the most simplest, it only needs discipline and consistency to succeed. Investors who are desperate for profits will not make potential profits, 8-10 years can be a long time of wait but it is fully worth the period of holding.
Trading is risky, trading is based on probability and possibility even with good trading knowledge, making profits isn't guaranteed.