This topic is as wide as the ocean, and something that takes years of careful observation and record taking to get a handle of.
Very generally speaking (and this is my opinion from my data collection, so nobody jump me!) after a long patch a poor weather once the baro starts to rise steadily is generally good, then the first day of stable pressure also good.
My personal favorite time is at the end of a long stable patch as the baro starts to plummet. In natal this is generally after several days of north easterlies, in the dying hours before the west comes through.
Having said this there are still many things to factor in such as water temp, wind, your chosen location, time of year, species your trying to target etc.
Hope this helps