Generally, there is a 12 bar hold after a signal change. That is the optimized value from past data since 2001. If the market doesn’t fall, then next buy would be Tuesday March 28 after market close.
The Tom DeMark 13 count sequence signal is well regarded. It is rare and indicates a possible market turning point. The last 13 count sell signal was 11/18/2021, 1 day before the market top. Tuesday 3/21 was another 13-count sell. If it plays out like last time over a year ago, the market could start fall in after today. Not a prediction, there is no grantee it will play out the same.
For a good market analysis I recommend the Chris Ciovacco Capital YouTube video published every Friday evening. It is about 35 minutes.