This is probably the second question most often asked when starting out with cloth (first is, "Which system should I choose?").
In my experience, we started CDing when Ash was about 5 days old and we typically went through 10-12 diapers in a day. Infants poop a lot more, every time they eat, actually. So that's every 2 hours within a 24 hour period. But as they grow older, you'll be needing less and less diaper changes. Ash, at 5 months, poops an average of twice in a day so we go through diaper changes 6-8 times in a day, sometimes less.