I felt little flutters (felt like irregular spasms) at 18 weeks, but weren't distinct until 20ish weeks... I seriously just woke up one day and he decided to start karate chopping my insides lol now at 21w6d you can feel him from the outside & see him.... it's amazing how quickly things can change in just a few weeks! Soon, mama :)
for my first it was around 17 weeks but it was just small movements that I didn't really feel unless I was laying on my stomach. For everyone it's different! don't stress! also depends on the position of your placenta.