I single side fed until about 5.5 months, except during growth spurts. I liked having the other side available for those times. Around 5.5 months, since I knew we wouldn't be starting solids for a while, I started both sides (as well as before naps) in an effort to get more in him during the day. It helped with his longer awake times during the day and naps, but didn't help the nightwakings at all. Now that we're on solids, I do both sides some of the time, except in the morning when I'm really full and one is enough (I pump the other side).