How much to bottle feed?

Br

So right now I'm EBF my 4 week old. I go back to work when he is 6 weeks and was told I need to train my little one now to take a bottle. I am only gonna give him one a day and breast feed the rest of the time. So I pumped out 3oz because I read that a 4 week old only drinks 1.5 to 3 oz of milk every 2 to 3 hours and my husband fed him slowly tonight. Well he loved drinking from the bottle but was crying when he ran out! Does he need more?? Or do I just give him time to realize he is full? Please help!