The most reliable approach is DCA in every phase of the cycle whether bullish or bearish. While no one can predict when's the exact "best time" to invest but historically a bear season is an excellent opportunity and we should try to accumulate more if we have spare funds because Bitcoin has proven to be bullish in the long term.
There is no best time to buy bitcoin but now which is the reason why you don't need to wait before buying provided that your discretionary income is available. Even during the bear season, nobody can know the bottom line of the dip which is a big challenge for those waiters and one of the major reason why you should keep your bitcoin investment ongoing regularly weekly, consitently and persistently for 4-10 years and above to enable you not miss out the opportunity of buying at the bottom line of the dip without timing it.
Only DCA can give you that opportunity to do so, which is one of the reasons why those in their accumulation stage should adopt DCA strategy to keep their bitcoin accumulation ongoing overtime.