I know this is not an exact science or anything - Tescos are doing a special offer thing where they swap ur clubcard vouchers for double the amount in tokens for a certain departments - so I had €55 in clubcard vouchers which I swapped for €110 in baby and toddler tokens - they have to be spend by the begining of June and babs is not due until september so we figured we are going to buy the mother load of nappies, wipes etc - real practical stuff that wont go off and will be brill to have - we were pricing them up and we were thinking of getting 3 boxes of pampers newborn 6lb to 13lb (264 nappies) and 3 boxes of the next one up I think 10lb to 20lb (288 nappies) is that a mad amount of nappies - what u think? I was working things out based on about 5 nappies a day - I have no idea!!
I can't remember on DD1 but DD3 was tiny when born so was in Size 1 (sorry don't know the weights) until almost 3mths (she weight 5kg at her 3mth check), then into Size 2 but only for short while.
She has just gone into size 4 this weekend. We still have a few size 3 for during the day, but at night she definitely needs size 4. She weighed 9kg at 8.5mths.
I don't remember how many nappies she went through in the early days as we used reusables but now she's going through 5 per day, some days it's only 4.
I can't help you with the nappies (I was asking a similar question myself only yesterday) but Tesco are great for other things like baby monitors and they often have the best price when you shop around. You could consider buying something like that to use up a chunk of the vouchers and then there's less risk of having loads of nappies that you don't use.
One thing I only discovered yesterday is that the size 1 and size 2 newborn nappies are very similar in weight, so maybe go for a small size and a bigger size (3 or 4) cos you'll definitely need the bigger ones.
In early weeks and months, you will need at least 8 nappies a day i.e. a nappy change with every feed. DS is 11 weeks today and we're now on 7 nappies a day on average. Hope that helps with your calculations
When DD was born she was 6lbs 10oz and we had to double down the size 1's for a few weeks to get them to fit on her! LOL!
Its a long time now but I remember not using very many size 2's for some strange reason!! I think we used about 6-8 nappies a day in the first few months.
She's only in size 4+ now but we are peeing in the potty etc so don't use very many!
We also didn't use size 2 very long. I currenlty have 4 packs of size 1 and 2 packs of size 2.
I'd look out for the special offers they have on the bigger boxes of size 3 and 4 etc. While you feel that's ages away you'll be surprised how quickly the time arrives. Also they are so expensive! DD was starting them the same time we were thinking about weaning (well she was starting size 4 then) and with the added cost of buying all the bowls, spoon etc it would have been nice to ahve nappies there. Even now if I see the boxes on offers I bulk buy, could buy 200 nappies in one go. DH thinks I'm mad but we save a forutne and never run out