I think you can spread the 2, 4 & 6 month jabs much further apart but I'm sure how much? Last time I did them 2 months apart but I realised later I would have been happier to leave them longer, and I'm sure they're still fine. It think they are effective from the first one- it's just how long that lasts that is the question. If you ring the immunisation line they should be able to tell you how long you can wait.