I had a small amount of things before we conceived (wraps toys etc).

DS1 put all big stuff (cot, pram, change table/tall boy) on lay by as soon as we had 20 week scan (at 16 weeks we picked what we wanted and had quote written down). Then bought clothes and things as time wen on.

DS2 didnt buy anything till 26 ish weeks and only some neutral clothes.