According to multiple analyses on average daily bitcoin prices, Sunday and Monday are the best days to buy BTC. The sole reason behind this statement is that prices tend to be at its lowest in those days. There are 3 theories why BTC price is good to invest when sunday and monday. The first theory is that on the weekends, the market for Bitcoin slows down, driving its price lower on Mondays. Bitcoin prices, on the other hand, are predicted to be high on Fridays and Saturdays. The second hypothesis suggests that during the weekends, people plan to buy BTC, and execute orders as soon as the week starts. Volumes on Mondays are higher in this scenario and more cautious conduct is predicted as the week goes by. And the third theory is Usually, seasoned traders will avoid purchasing bitcoin on dates to pay 9-to-5 staff, usually in the middle and end of the month. The reasoning is simple: Bitcoin can be purchased when people have money in their wallets, pushing demand, and its price higher.

Source: https://crypterium.com/news/post/what-is-the-best-time-to-buy-bitcoin