First, Welcome to CDC!!!
Regarding your question, I'd keep fishing (you said you've caught abot 150 or so) until they slack off. I can't tell you the 'exact' time they will move to deeper water (it would be helpful if you indicated how deep you're catching them as well as the avg. depth of the pond and if you're fishing from boat or bank, etc.) .. lots of unmentioned variables.
Regarding jigs, I'd say 'experiment'. Jigs are relatively inexpensive, so it isn't unheard of many crappie fishermen with 50+ jigs of different colors and shapes.
Basically trial and error :o You'll have fun in the process! Pay attention to different patterns, etc. you're using to catch fish.
Just my $.02 ... others with varied opinions may chime in
Good Luck!