What age will my daughter start saying words?

I'm just curious as to when my daughter will start saying some words? My oldest who is now 2, said her first word mama at 3 and a half months and kept saying it, it wasn't just fluke lol. I know every baby is different but my youngest is now 6 months and hasn't said anything not really even babble just silly sounds and stuff like that. So i'm just wondering when did your 2nd baby start words? I really want her to say mama soon lol