Hi B.,
First, don't worry so much about the bedtime as about the total hours of sleep your son gets in a 24-hour-long period. That being said, 10-11 pm sounds a bit late for a bedtime. First, I'd make sure baby isn't getting too much sleep during the day in naptime. The average baby this age needs 14 hours of sleep per day, but your baby's needs could vary as much as 2 hours in either direction. If he's sleeping about 11 hours per night (and waking up at 8 or 9am), plus getting about 3 hours sleep during the day in 2 good naps, he's getting all the sleep he needs, so you just need to adjust the time.
If he's not getting too much sleep in naps, I can recommend the following. It worked for my little ones when I had to change bedtimes in either direction. Start putting him to bed about 15 minutes earlier than normal, keep that time going for a few days - maybe 5 or 6 or longer if baby is waking and ready to go after a brief nap at this new bedtime. Then make bedtime another 15 minutes earlier, and repeat the process over and over until you have a bedtime you are happier with. If you are going for 2 or 3 hours earlier, you should expect the entire process to take 8-12 weeks.
If baby is sleeping more than 4 or 5 hours during the day, or taking more than 2 naps, its time to cut out a nap and shorten them, probably not letting a nap go longer than 2 hours and not taking more than 2 naps per day. (I know, I hate waking a sleeping baby too! But the reward is an earlier bedtime, something he will definately need as he gets older.)
Last advice, if you are rocking or feeding baby to sleep, or if baby isn't sleeping through the night, its going to be a lot harder to do this. A baby this age is old enough to learn to put himself to sleep and not receive night time feedings (unless your pediatrician advises otherwise). Time to teach self soothing and teach your baby to fall asleep on his own. You are doing baby a favor teaching him to sleep on his own. Its a skill we all need to learn.
I hope that helps. Good luck!