Personally I find this the best option for SFO-SYD :

* Have either a very late lunch, or a normal lunch and a very light dinner
* Eat the "dinner" meal on the flight when served, which is around 5pm Sydney time
* If needed, partake in the exotic mid-flight snack (aka a fairly basic sandwich)
* Have breakfast when served - it'll be roughly breakfast time in Sydney

I find doing this means that I arrive in Sydney pretty much on schedule meal-wise. Trying to shuffle things around might make more sense based on SFO time, but not based on Sydney time.