When did your belly pop out?

Tw

Hello! I am currently 8w+4d with twins. I am just wondering when your belly pops out? It’s my third pregnancy but first time with twins. I imagine we are all different. I only ask because I feel like some days lately I can feel my lower belly pop out and days like today it feels like it’s been sucked back in. Am I the only who who has experienced this? TIA 😇