A good 10 ounces of water was poured into my 2008 15" MBP by my son. I powered if off as soon as I could and waited. I tried powering it on after two weeks - no go. I tried again after three weeks - no good. I tried again after a month - still no good.
At that point, I wrote it off and started looking for its replacement. I was almost going to pull the trigger on a purchase late one night, and opted not to because I was too tired to fill out the info. The next day I was in my office, intending to place the order when I said "what the heck, I'll try one more time." And hit damn, it turned on!!!!
Six weeks after taking its bath, it was up and running again. The battery lasted for another two years, and the misses is still using it(RAM and SSD upgraded) today - six years after purchase, and three years after it's bath.
I did not use rice, but it was in a dry place.