It really does depend, I guess. With this pregnancy I expected to show early or at least earlier but I'm still tiny! I could pass for not pregnant as recently as a few weeks ago (at 20w, I am 24w now) and can still wear all my prepregnancy pants, including skinny jeans... not sure where bub is hiding as I haven't put on any weight yet, still under 60kg. My belly has just recently started looking rounded and I can sort of see the definition of my uterus but yeah, everyone has been commenting how small I am (which people seem to think is what you want to hear but really just makes you worry lol)... expecting it to explode any day now. I was similar last time so I guess that's just how I carry. Maybe just see how you go and if you do start showing you can bump telling at least the most important people earlier? We didn't tell anyone till I had had my 20w scan and not even my parents who I see at least weekly guessed which if they had, they would have said something! They were still making 'she needs a sibling' comments right up till I announced it to them.