Welcome to Bottle feeding Sara
If he drains a bottle, add an ounce to his feeds... chances are he can go 3 hrs between feeds...
As for how much at each feed - it does really vary, but there are a few guides out there... one is 4 ozs by a month of age with a further ounce for each month of age (can be way off because of the variation in size of babies!)... the other is 2.5 ozs per pound of weight per 24 hours...
So, a 10lb baby would be about 25 ozs/day total
That said, some kids drink a tonne and others max out at less than the "recommended amount." Laura's kids maxed at 25 ozs a day (both were refluxers) but both were also 90th centile and maintained just fine! Mine is an average bubs (50th centile for weight as an infant) - she was taking around 24-26 ozs at T's age... If I remember right, her feeds were about 5 ozs each at this age...
I always spaced feeds to ensure she would drink her bottle completely (or very close)...
Other things to consider with FF:
1. time between feeds is often a bit more than with BF (we were at 3 hrs easily at 2-3 months) and moved seamlessly to 4 hrly at 3 months 3 weeks after 2 weeks of her not finishing her bottle and being fussy (took me that long to figure out that she wasn't hungry yet!).
2. some bubs need a burp every couple ounces, others don't at all until the end of the feed.
3. feeds should take a max of 20 mins (if taking too long, might need a faster teat
).