Well i've done it lol
Bought and downloaded the knitting pattern - looks straight forward but I'm sure they'll be a point where I'm going to scream and go arrgh what was I thinking?!
Now..i'm thinking size. Baby is technically 3 weeks old...currently we're entering summer (if you can call the UK actually having a summer...sizes for this pattern are 0-6 months, 6-12, etc.....now...would knitting the first size be a bit silly for now? or should i knit for 6-12, in which case baby would be 6 months in November..but don't know how much wear a baby would get in a waistcoat in the winter period..i mean, babies need to be kept super duper warm right?