First of all, I would steer clear of any kind of schedule. Or at least a strict schedule. Routines are great, schedules not so. Watch his cues, not the clock, and there is your schedule. And count on it to continue to change.
Other moms are telling you he must go to bed earlier. I think it depends on the routines and order in YOUR house. My baby just happend to have a later bed time, yet slept later in the morning and took great long naps during the day. He always got the amount of sleep he needed within a 24 hour period, just in the order he wanted it. And it jived just fine with the rest of the household, so no problem.
My guess is he's saying either he's sleepy around 8:30 and needs that to be his bedtime for now or the bath is too relaxing and he's anxious to fall asleep soon after. Maybe delay the bath. Or simply let him stay up for a later feeding. I worry when you say "I would like for him to go to bed by 8:30 or so". Having a routine in your home will benefit baby and everyone else. But be wary of setting a time for eating and sleeping. Your baby will go through so many changes in this frist year, that almost as soon as you pick a time, he'll mature and hit growth spurts, and need to adjust those times. How is he napping during the day? How late does he sleep in the morning? All these will factor into his "bedtime."
Here are some links you may find helpful...
How Much Sleep Does My Child Need
http://askdrsears.com/faq/sl17.asp
Sleeping thru the Night
http://www.kellymom.com/parenting/sleep/sleep.html
Newborn Babies and Sleep
http://www.kellymom.com/pantley/pantley03.html
Will Giving Solid Foods at night help baby sleep longer?
(BTW, the answer is no. And be sure to check out the links at the bottom of this page. They are real eye-openers!)
http://www.kellymom.com/nutrition/solids/solids-sleep.html