I think the earlier you start buying, the better. That way, you're not going to really notice the $$$ you're spending. I bought mine all in one go, so I really noticed how much I'd spent. IYKWIM.
It's good to buy a couple of different brands, and different styles as each baby will be different. On my 2 year old, I prefer the fitted nappies, and on my 3 month old, I prefer the AIO's.
If you buy mcn's which have a good name, and they don't suit your baby, then you'll be able to sell them at a reasonable price as well.
Once I taught my dh how to use the nappies, he was ok with it. But he was just as keen to use mcn as I was, so that helped. He might find AIO's easier to use than pockets, or fitted.
HTH.