I think it depends on his weight & age! I got a list from HK Baptist Hosiptal for your reference:-
2.5 - 2.79kg daily recommended volume 14oz (1wk)
2.8 - 3.49kg 18oz (2 wks)
3.5 - 3.99kg 24oz (3-4wks)
4.0 - 4.99kg 25oz (2mths)
5.0 - 5.99kg 30oz (3mths)
6.0 - 6.49kg 35oz (4mths)
6.0 - 6.99kg 35oz (6mths)
7kg or above 40oz (6mths or above)