There is no specific time to invest. You can invest whenever you want using DCA method.
The right time to invest is when you have seen that you have your discretionary income ready, Bitcoin investment is a long time investment so its not what you should invest with money you can't afford to loss so a specific time to invest is when you have a leftover income which is your discretionary.
Secondly waiting for the price of Bitcoin to dip before accumulating is a trader strategy and target when there is an increase to sell Bitcoin is a volatile asset it might still dip while waiting to increase to sell so it's always best to accumulate Bitcoin and hodl for long always keep accumulating and hodl, the DCA is guild to regularly accumulate Bitcoin weekly or monthly regardless of it's price and hodl for 4-10 years.
In no case should you wait for the price to fall or rise, this is already an attempt to become a trader. But in reality, no one knows whether the price of Bitcoin will rise or fall tomorrow.
We should not wait and guess, you just need to invest constantly and maintain investments. I mean, we cannot invest today according to the DCA, and in a week, due to everyday needs, transfer money to fiat, because we wanted to buy something.
This is not investing, but deceiving ourselves. And I am sure many do this due to weakness of character. This cannot be allowed.
Strength of character and the ability to not change of our views will be rewarded.
Those you might be seeing selling their Bitcoin just because they ran into problem are doing such because they don't understand the value of have an emergency fund at hand. There are many traders and investors that had made this mistake in the past and it wouldn't make sense for us to make the same mistakes again. Crypto investment should not be seen as a means of making quick profits from the market.
The DCA strategy is meant to guide every investor to be very conscious when making an investment so they don't suddenly cripple their own investment as a result of not have a reserve or emergency fund that could prevent us from selling our crypto portfolios just to settle the problem in hand. The crypto market is broad and it should be understood that investing in Bitcoin can be highly profitable when we tend to hold for as long as possible; this can be done for as long as possible so the investment can grow well and gather substantial profits for us.