When did you buy your pram/big baby purchases?

Faye • 26 • Erin - 20|08|15 - 9lbs • Bonnie - 19|08|18
When do you think is too early?
I'm going to go and look at stuff when I am about 16 weeks but I'm not sure if I should actually buy anything big at that point. 
I don't live near any of the big stores though so were going to be driving out to look at stuff. 
What do you all think?