Hi I.,
I totally support your decision to do this. I have often wondered about how wise it is and if it is overloading the immune system.
That said, here is one factor to consider. According to our ped, one of the reasons they do it that way is so that the child doesn't associate going to the doctor's office with pain. On the regular (not spread out) vaccination pattern this is not a problem.
When my son was a toddler, he had to go through a lot of different medical tests. He became terrified to go to any doctor's office. For years afterward, he refused to let the nurse weigh him and resisted being touched by the doctor, even just for a regular check-up. It was bad. I would hate to see you go through that.
I'm not sure what age the fear would kick in though. Maybe 9mo? 12mo? So maybe you could spread them out for the first year only? But be sure to check with the doctor that there wouldn't be any issue with switching back to doing them on the regular schedule.
-D.