Depends if u're gg to mix bottle and breastfeed. I standby 3 Avent 125 ml bottles (so tt can last till abt 2-3 months). For the 1st mth I do bottle feed only abt 2-3 times a day when I need to bathe, massage etc. Best to limit bottle in the initial weeks as baby is still learning to latch.
Newborn doesn’t drink a lot so the smallest bottle of the brand is good enough (for example hegen the smallest is 60ml, otherwise you can get 150ml, it’s fine too) and I get 2 bottles just in case one bottle doesn’t dry before my baby next feed.