Usually around 30 days. You can strip them at around 20 days and the fry will have absorbed half of the egg sack by then. That is my experience with c. leptosoma, not sure about the Jumbo's though it's probably the same time frame.
I understand that temperature plays a large role in the development time of the fry. I keep my fry tank a couple of degrees warmer than the main tank. And of course there is no substitute for clean fresh water. Keep up the water changes :fish: