It is possible that a 3 month old can take all he needs in that quick amount of time and that the crying you are experiencing is due to something else. Is this possible? Also, at 3 months, there is a huge growth spurt so you might want to feed at your scheduled time, feed again in one hour and follow that throughout the day for the next 4 to 5 days. After that, see where you are and get that little one back to a regular 3 hour routine. Do not continue allowing snacking after you've ruled out a growth spurt. Good luck