Teagz - sometimes it depends on your flow, i would leave a 1 and a 2 JIC, are you able to maybe try and see what works at home first?
I am thinking about this with Z aswell, i have expressed a bit today and want to make it a regular thing for DP to feed Z so i can have a break and get her used to a bottle, i have quite a fast 'flow' so am thinking she might prefer a 2.... hmmm interesting to see what everyone else suggests.