It's different for everyone, but most people do show earlier with their second. I never got back to my original figure, so I always had a tummy on me, but when I found out I was pregnant with # 2, I only had a week or 2 before people started asking if I was expecting again. Of course it's not a baby belly, but bloating, but apparently it was still obvious. I ended up telling on Facebook before those that saw me in the street could blab it on there for me.
Just so you can compare though; the first photo is me at 14w with my first pregnancy, and the second photo was me at 13w4d with my second - only 3 days gestational difference. Amazing really.