Pumping for work

Maybe a silly question, but I'm new to all of this. I am going back to work in a month and need to start storing some milk for when babe goes to daycare. I know I only need really for the first day or so then ill pump at work for the following days. My question is when I feed him, we only do one side at a time for the entire time and I usually have my haaka on the other side. Can I just pump the one side at a time while I feed him from the other side or do I need to wait and pump both sides after hes done eating.