Buying diapers ahead

Hailey • Engaged to my love and just had our first son, Riley Knox💙🌞🍼
So I've really been thinking about starting to buy a box of diapers a week in different sizes to stock up. My friend said it's cheaper to buy the huge boxes on amazon than Walmart. My question is I just don't know what sizes I should buy more or less of. Or if this is even a good idea?? Anyone else done this before? ?