Having more kids

When did you know if you did/did not want more kids? I always thought I'd want 2-3 and my husband always thought just 1. After having our first (he's 5 months) I'm thinking I don't want anymore. I love my little one so much and I just don't really picture an additional one in our family. Will this outlook change as he gets older or is it when ya know ya know? What's been your experience?