At one point or the other, we all need to buy bitcoin, but when do you actually buy it? or when is the best moment to buy bitcoin?

For example, should I save some cash to but bitcoin when there's a 0 -15% dip? or should I wait till there's a major drop of >30%?

Is DCA the only way to buy bitcoin? What if I invest in an altcoin that booms and then take profit from it to buy more bitcoin?

What is your strategy to buy bitcoin?