Advice- vaxing 2,4,6 yr old

[Dandelionkid]

I think I messed up. I really did a wishy-washy schedule with my kids and they only received the quadracel (dptp) once a  year, my son had 2 doses in 2 years. The package insert says that the first three doses need to be 2 months apart, even if delayed. Does that mean that my son needs to start all over to get the dosing every two months or can I give him his next shot as his third dosing?

Thanks!!