Quoting firecop:" I know the first child you have takes a lil while to feel baby kick. You can feel the 2nd child kick ... [snip!] ... with the 1st. When is it that you can feel kicks and movement with the 3rd child? How soon with the 3rd, do you start showing?"
Every person is different. I just had my first last September and felt light flutters at 11 weeks and actual flutters at 15 weeks and full kicks and hits by like 18 weeks.
And every pregnancy is different for the same person. My SIL's second pregnancy she was showing just around 8 weeks, she was tiny we all thought it was twins. Now on her 3rd pregnancy she's been feeling her LO for a long time but just started showing around 26 weeks.