From my little experience with the Bitcoin Investment system, the best time to buy the coin if you are targeting to make a profit in the bull run is during the bear run. The price is cheaper and you can make a good profit within the four-year circle. At this period you don't need to rush to buy because of FOMO but you can comfortably buy at your own pace using the DCA or other strategy that suits you.
Cryptocurrencies like Bitcoin can experience daily (or even hourly) price volatility. As with any kind of investment, volatility may cause uncertainty, fear of missing out, or fear of participating at all. When prices are fluctuating, how do you know when to buy?
In an ideal world, it’s simple: buy low, sell high. In reality, this is easier said than done, even for experts. Instead of trying to “time the market,” many investors use a strategy called dollar-cost averaging (or “DCA”) to reduce the impact of market volatility by investing a smaller amount into an asset — like crypto, stocks, or gold — on a regular schedule
DCA might be the right choice when someone believes their investments will appreciate in the long term and experience price volatility on the way there.
There's no specific time for that since you can able to invest any time you want. But make sure you have knowledge about what you are doing before taking some risky decision. If you are not confident on your knowledge since you think there's a lot of things lacking then get afraid to lose some money for it then I guess you better need to get more knowledge so that you could able to start on your investments.
DCA is one of good strategy to use. But now everyone can able to execute this well, so better start first on something that can give you a lot of knowledge or experience since once you learn from all of the experience you got from here then I guess you could able to decide what's best for you and can determine those important things to avoid.