I only ever used the square ones, but I'd definitely recommend finding big ones, can't think what size right now, but big ones are easier to wrap with. With a winter bubba I'd suggest flanellette ones, if you're a sewer (or even if you just have a machine) you can get flanellette cheap & just hem the edges up but make sure there are no lose threads.

For singlets, I'd suggest around 9 or more (??). That way you have enough for three per day in case they get spewed, weed or pooed on & you don't *have* to be washing every single day. Others might think differently though.

It's funny, Zander is 2 and we aren't even 1/4 of the way through his second bottle of shampoo hehe! And remember they don't have to be bathed every single day and not really with soaps until they are crawling round getting dirty, so they aren't essential to start with.