I started buying things about 15 weeks. And the last month or so I've gone nuts..I've bought a cot, pram, baby rocker and baby playmat. Getting all the heavy things out of the way before you are HUGE is a good idea. And buy some clothes/toiletries every pay day or so, that way you don't have to spend a whole lot at once. If you can get stuff given to you, that's great too...clothes are very handy, and baby baths, toys that can be washed etc..