The best time to invest in Bitcoin is at the lowest price that will never be seen again. If we will never see below $20k prices again, then any purchase made 7+ months ago was the best at that moment. But now that we're experiencing an almost 50% crash with very weak recovery, it's very debatable whether it's the best time, or if the price will go even lower. Of course you can win big if the bull run resumes tomorrow, but you can also make a suboptimal purchase if the price will keep sinking.