My first child

How can you stock up on diapers till they start potty training? they come in different sizes and the kids grow. How do you know how many of each size to get before they will grow out of them?

It's best to buy them as they grow....

Same with clothes.

We had 2 boys. One was born in July, the other six years later in October. They were not the same size at the same season for the clothes to fit... IE summer clothes, winter clothes... They were "out of synch" with the seasons because they were born at different times of the year from each other and may grow at different rates...

If you "jump the gun" and buy too many things up front, then you may get stuck with some things that you never needed.