During the bear market, those that have experienced it before will say that it's the best time to stack bitcoin. Because the price of bitcoin by that time is cheap and many don't feel that they should buy it as everyone is selling and has the same feeling, fear.
Evaluate dollar-cost: [..]This means investing a fixed amount of money at frequent intervals, regardless of the price. This can help you avoid buying at a high price and losing money.
There's also the understanding of DCA and that is to buy at any time that you wish. The intervals might not be the same and no patterns, as long as you get to buy it whenever you've got money and yes, that price don't matter at all because as soon as you've got money ready for buying, you'll use it.