My doctor said it would be better if bb is 4 mths when inject the肺炎針. i.e.4,6,8 for the 1nd,2rd,and 3th肺炎針. Then 1 year old for the 4th肺炎針. Although the肺炎針 is suitable for bb since 2months, he said the effect is good in 4 months bb rather than 2 months bb. So I follow his instruction.