How to start storing

When my little one was born he was in the nicu for the first 4 days until we went home. I started pumping right away. Now I'm getting about 4oz every 3 hours. He eats about 2-3 oz every 2 hours. I'm wondering how to get ahead of him enough so I can start storing for when I return to work in July. I also do not pump during the night but will get 8 oz in the morning when I do pump.  Thank you in advance for your input.