Depends if you get a whopper or not. DD wore 00000 for at least six weeks and then 0000 for a couple of months after that. DS wore one outfit that was 0000 and that was cos I squeezed him into it to go home from hossy lol. Get mainly 000's. You can always get smaller if necessary. I found that singlets one size up are better anyway. Easier to get over wobbly heads.
I'm also a fan of muslin wraps, singlet suits and just a nappy. My kids lived in them. I'm not a fan of 'outfits' cos they're fiddly and either get pooed on or puked on or dirbbled on - but each to their own.
If people want to know what to get you, tell them to get stuff in bigger sizes. Always nice when you've realised that they don't fit their current sizes anymore to have some thing on hand that's bigger.
Don't forget to also get a couple of little pairs of socks. Genreally you'll be inside over summer and usually in some sort of cooling adn their little toes do get cold.