I almost always used around 30% Hi-Octane in my CITY-2009 (with ECU reprogrammed). It was not intended entirely to avoid knocking problem (that actually was not there at all) - but to enjoy the extra bit of power. Moreover, I got a bit better consumption with Hi-Octane in the tank (hence somewhat off-setting the extra cost).
From my experience I will recommend to use Hi-Octane.
I normally go to CALTEX Filling Station in F-6 (Super Market) or Shell in F-7.
Congrats on getting new car. May you get to enjoy the drive of this wonderful car.