I made most of our diaper stash and used flats and prefolds to fill in the holes. DD was born at the end of May last year and we did coverless with our DDU fitteds and EZDipe2 fitteds that I made, and then also with flats in a kite fold with a preemie doubler, or orange GMD snappied on. She peed so often that I just changed as soon as wet and we never had an issue. At night, we would just use a diaper with more absorbency or add a doubler and then put a cover over the top. We changed once or twice in the middle of the night until she was about a month old, and then we switched diapers and she would stay in the same diaper all night.
I love flats! I think I may just do them. With ds2 I did orange edge prefolds as well but got rid of them after the flat love. I hvae in my mind that I need fitteds for that absorbancy. Maybe it is a cuteness factor. I do have a ton of AIOs. But the other thing I am worried about is the size of baby and AIO not fitting until 8ishlbs.