My small diapers didn't start until 10lbs. I regretted not getting the newborn size last time around because of that. I personally would not want to do diapers every other day with a newborn and a toddler - I'd get 36 diapers.

I have 12 pre-folds and covers, and 12 pocket diapers. I plan on doing laundry every-day. I would imagine 24 is a good number. Its hard to by more than that, because they are soo damned expensive!!!!

I bought some newborns, but only in the pre-fold covers. I will be using disposables for the first few weeks....frankly, this is only because I could not afford to by a whole new size of diaper.

24 sounds good. 12 a day is reasonable, especially without blow out meconium diapers.

Thanks for the input guys! I have a better idea now of how many I need.

So, I'm pretty amazed right now - I just counted all the diapers we already have in small and realized it's 37! These are all infant prefolds and flats that I bought as pocket stuffers or doublers ages ago, and some extra I'd bought used off a friend a couple months ago when I was obsessed with TTC. LOL! So now I just need covers or pockets to use them with. Oh and I have a few one-size bGs from diaperswappers already that I'd been using with DD.
I'm participating in a co-op for some cheap pockets and scouting out used covers. Hoping to find them locally so I don't have to worry about shipping or currency conversion, that's a pain. Still debating how many to get. Not sure if it's better to buy less in case I find I don't need as many and buy more if needed, or boy more when I can scope out deals and sell them later if I don't need them. Hmm..

I KNEW the fluffy love was going to return at some point. It was only a matter of time...

You need less covers then you need diapers. As long as a cover doesn't get wet or soiled, it can be re-used. We have enough diapers to go 3 days without washing, and we have 4 procare covers. One for each night, and one for extra just in case. I recommend bellabottoms pro-care covers if you're looking against leakage, nothing gets through these ones, though they are really bulky on new babies, we couldn't start using them until Theo was 4 months and they were still humongous on him

We also have a lot of wool covers, you can buy REALLY inexpensive soakers made out of recycled wool sweaters. With knit wool covers you need to hand wash them, but for a lot of soakers, they're pre-shrunk, so you can still throw them in the wash, the only extra step is to lanolize it once it's clean. With wool, even when it gets wet, you can keep using it just as long as you air dry it between uses, it can go like a week without being washed. The lanolin makes it antibacterial, and it absorbs urine and then turns it into like.. crystals.. not explaining it right, but it's like febreeze, it absorbs then gets rid of as long as it's lanolized.

You can also get really cheap fleece covers, fleece need to be washed after each use if it gets wet, but they're so low maintenance, you just throw them in with the diapers and they don't need to be lanolized, it's a barrier cover, so liquid doesn't go through. Most of our covers are recycled wool or fleece or interlock or knitted because they're less bulky and breathe better, the pro-care covers we only use for night times.

I used 12 small diapers and 5 newborn and mostly washed them everyday...occasionally stretching to two days.

In a pinch, you can origami-fold a receiving blanket (or any absorbent square material) and pin or cover. It works well and washes/dries super fast.

Hah, that's too funny that you mention that! I totally origami folded a receiving blanket a couple days ago just to see if it would work... It did!

I, right now, use fewer than 12 a day, but we also spend some time diaperless each day. I think that's a fairly reasonable estimate, though. You can also use cloth diapers for just about anything else, so it's useful to have a few extras around anyway.