A 3 month old should be eating more than 4 ounces at a feeding. He could probably have 6 to 8 ounces every 3 to 4 hours during the day. She also needs to set a first morning feeding to get his routine started, but it should be eat, play, sleep on a rotating 3 or 4 hour schedule. So, if you start with a 6am bottle, he should then nap from about 8 to 9:30, another bottle at 10, followed by an hour or two of play time, then another bottle around 2 or 3, then play and a nap, then a bottle at 6. Note that the times are approximate. He could go 3 hours for one part of the cycle, then 4 hours for another part, then 2 hours the next time. The important part is the order of things: eat, awake time, sleep. The 6pm feeding would be followed by bed time routine stuff -- play, bath, read books, then bed time around 8:00. He might wake again around 10:00 for a bottle, then be put right back to bed without the "play" part of the cycle.
Also note that he probably can't stay awake longer than 2 hours at a stretch. Staying awake longer, even if he seems perfectly happy, may over-stimulate him, which can make him not sleep well.
Another pattern for the afternoon/evening might be a longer afternoon nap with a short evening cat-nap. Both of mine did this: after the 10am bottle, nap from about 11 to 3, take a bottle, play for a while, then take a short half-hour to an hour nap at 5 or 6 (for my daughter this was usually the ride home from daycare), then have a bottle at 6 or 7:00, then get a bath and bed time story and go to sleep for the night for 10 -- 12 hours. For my daughter, bed time was 8:00 (with no additional bed time bottle). My son would crash at 7:00 and to this day (20 months) will usually be asleep by 7:30.