You can definitely cloth diaper from birth; no need to use disposables for the first month, although some prefer to use them until the meconium as passed and/or the cord has fallen off.
Thank you so much for sharing your wisdom on this! It's my first, and I really want to use cloth, but am totally clueless.
How hard is it to get the meconium out of cloth? Does it take a lot of soaking?
Can you share what kind of one-size covers you've used that are waterproof?
What are the flats?
The meconium is water soluble and so washes out easily. It will leave some staining most likely, but if you dry the diapers in the sun, it will bleach out. Also, exclusively breast-fed poo is water soluble so you don't need to soak or spray or anything. Just chuck everything into the washer and it will wash out. Again, drying in the sun is best for avoiding staining, or you can use chlorine bleach if necessary. Just be sure to rinse and rinse and rinse until you can't smell bleach in the diapers anymore.
There are LOTS of one-size covers out there. For the newbie stage I like the Thirsties Duo size 1. They work well over fitted diapers and fastened prefolds or flats, which are the kinds I like to use on tiny ones. When they get older and I start pad folding flats, I like the Flip covers the best. I have heard really good things about the Diaper Safari and Diaper Rite one-size covers, too, but haven't tried any personally yet. Of course, there are lots of covers on the market and I've tried most of them and wouldn't say that I've found any that I thought were terrible. It's more just a matter of personal preference and, for me, the simplicity of a more streamlined stash.
Flat diapers are the big one-layer squares of fabric that have to be folded. They are usually birdseye cotton, though some places also make them in linen or even bamboo. I like the Diaper Rite ones from Diaper Junction - small for little babies and large for big babies/toddlers. Like I said, I mostly pad fold for my two toddlers (starting when their poop became more consistently solid), but plan to fold and fasten for my new one. I like the kite fold, neat fold, and airplane fold best.
For newborns, I prefer to use fitted diapers for the sake of containment of the runny poo. I like Kissa's size 0 (seen often abbreviated as KL0s - they used to be called Kissaluvs) quite a bit. Also, the Green Mountain Diaper workhorse diapers, which are basically a prefold converted into a fitted diaper. The leg elastic is just good insurance against those poosplosions that are so frequent!
Of course, a good cover will contain anything that the diaper itself doesn't.
Anyway - sorry for the novel. I hope it helps. I'm always happy to answer questions about cloth diapering!