How do I stock up breast milk for daycare?

I am a first time mom and my baby boy is 10 weeks old. I have to go back to work in about 5 weeks and I don’t have any milk frozen yet. How do I get enough milk to start freezing it? Right now I pump about 4 ounces a day. I pump 3-4 times a day and do it right after I feed him. Any suggestions?