Can you make the body of shakshouka the day before & then add pre-poached eggs to it while it's reheating on the stove the next day?
Absolutely. Just warm the base before you add the eggs because the eggs take so little time.
Oh...I just noticed you said pre-poached eggs. That sounds like more trouble than you need to go to. I poach/cook the eggs right in the base with a lid on.