My wife and I took our 3yo girl and 1mo boy to Cape Cod last year and, based on that experience, I wouldn't recommend a Disney vacation. We had a great time at the Cape because the house we rented was practically on the beach so we could easily adapt to whatever the baby needed at any given time. We could also split-up and adjust our schedule as often as was necessary. WDW would obviously be a very different environment. Aside from the health concerns for both mom and baby, which are probably valid, I don't think you would be able to enjoy the vacation anyway. Even in a best-case scenario, you're feeding, burping, changing, napping, and otherwise tending to the baby almost constantly at that age.