For diapers, average shld outgrow newborn size after 1mth -2mth..
S size are suitable for 3kg up..
M size around 6kg up.. probably around 3-4mths old..
dont need to stock up too many, end up have to sell away.
Just get one packet, if going to finish then buy.
For strollers, i got mine when i was 6mth+ pregnant.
Cus i knew around 8mth, im too tired to go around looking.
For playpen, i got pass down, almost brand new, cus some dont sleep.
save some money as well