As I've read on here over and over, and as my ped keeps telling me too - milk is lo's main source of nutrition until 12 months old... solids for us are for practice, table manners, and tasting new foods and consistencies, not nutrition at all.
My 7.5 month old drinks 4 10oz bottles a day, and has 2-3 meals per day, and we're still on purees!
I'd feed your lo as much as he'll eat... I think if I gave my ds more milk he'd drink it! (Our bottles only go to 10 oz!) I tried him on 10oz when we dropped the df, and he's been finishing that much ever since! I'm expecting him to want less since he's been on solids, but no such response yet!
Also, we feed ds his bottles on a 4 hour timespan, and feed solids in between there sometime, usually around 1.5-2 hours after his last bottle so as not to interfere with his milk intake.
He usually wakes around 4-5am where I give him a diluted bottle (3oz formula, 3 oz water) but last night he went right thru till 6:45am without waking!
My ds is also a big baby...not sure of his weight right now.
I don't know about the growth spurt at 8.5 months... hopefully someone else can weigh in on that...