You will need

Striped Version
0 -3 months (16in Chest) 1 Ball Main Shade and 1 Ball Contrast Shade
3 -6 months (18in Chest) 1 Ball Main Shade and 1 Ball Contrast Shade
6 - 12 months (20in Chest) 2 Balls Main Shade and 1 Ball Contrast Shade
12 - 18 months (22in Chest) 2 Balls Main Shade and 1 Ball Contrast Shade

Flower Version
0 -3 months (16in Chest) 1 Ball Main Shade and 1 Ball Contrast Shade
3 -6 months (18in Chest) 2 Balls Main Shade and 1 Ball Contrast Shade
6 - 12 months (20in Chest) 2 Balls Main Shade and 1 Ball Contrast Shade
12 - 18 months (22in Chest) 2 Balls Main Shade and 1 Ball Contrast Shade

3.25mm and 4mm Needles
3.25mm Circular Needle