24 weeks is a long cycle. How long have you been off, and are your hormones back to normal?
How long you run a cycle depends on a lot of things, one of which is the compounds you choose to use. If you want to run shorter cycles, say 6-8 weeks, I would advice using shorter acting esters. So in this case, in stead of Sust and Deca, I would look at Test Prop and NPP. It will require pinning more often, but the drugs will be in your system and working faster. If you chose to run Sust and Deca, I would shoot for a minimum of 12 weeks to get the most out of it, and maybe extend up to 16 or 20 weeks. If you are coming off completely and not cruising or going back on TRT after the cycle is completed, I would keep it to no more than 16 weeks. The longer you are shut down, the harder it can be to recover.
As far as dosages, I would run Test at the same dosage you ran your first cycle, and then add in the deca at 200-300mg per week. You may be able to increase deca to the 400-500mg mark, but you probably won't need that much for results based on your cycle history.