Hi shezomru,
I believe, in part, it depends on what your snake has eaten and how quickly the specimen metabolizes food. Pinkies or partial pinkies will be digested much quicker than an adult mouse because their bones and muscles are more fully developed. However, on average, I found that my pinkie eaters poo'd 3 days after a meal. When moved up to fuzzies they poo'd somewhere in the 3-5 day range on average. Now they're on small mice but I don't have enough data yet to give you an average, however my guess would be somewhere in the 5-7 day range. Another factor to consider is how large the meal was and did you feed multiples. Also, an active snake, that moves around the cage a lot, will be more likely to have a higher metabolism and digest a meal more quickly. I hope this helps!
Cheers,
Jason