I am currently 22 weeks pregnant and my 2 other kids I had a month early and me and my fiance was talking about all we needed to prepare for our sons arrival so is it too early to get a car seat?
I have had a carseat since I was like 14weeks! Better to be as prepared as possible as early as possible in my opinion!
Its never too early to be prepared
After 24-26 weeks because if u go into labor and they can not stop it and baby is born at 24-26 weeks they will use life saving measure to save baby before 24 weeks they consider a baby not viable outside the womb and won’t use life saving measures on baby
I literally just got mine I’m 36wks lol 
but I’m late to the draw this time around, but I’d say by or at 30wks or so at the latest!
I’m superstitious so the car seat was bought when I was 36 weeks pregnant. You don’t actually need to buy it before the baby is born and any baby born early will most likely be kept in for a few days.