Hi,
We were planning to go and buy stuff around the 20 week mark this time! Unfortunetly they had a sale at baby co and that was it before we knew it we'd bought the whole lot!
Pre-warning some places have to order in it took 8 weeks for our cot to arrive!
My nursery was completely finished by the 25 week mark this time!
With my first 2 we bought stuff from when we knew I was pregnant and I still had alot of stuff from my second, where as this time we didn't have anything as we'd given in all away!
If I was you I'd start with the big stuff either purchuse or layby then move down to the smaller things later! That way if bubs arrives early you've got some of it organised!

Best of luck!!!
Snoopea