I don't and have not for a very long time fed puppy food, from the time my babies are starting solid food, it is adult food, the same as the adults. If you are using a good quality food there is no need for a puppy formula, IMO.
I also don't agree with free feeding, does not teach your pup good eating habits… Food goes down for 10 minutes, taken up eaten or not till the next feeding time. Pup at 8 to 12 wks, 3x's a day. After that 2x's a day, with snacks once or twice inbetween. For sure a cookie or two (small ones) before bed time.
I don't use anything with corn... Eukanuba has corn (or at least it did). I use grain free. Love Fromms surf and turf... among others. And I switch up brands often, that way I never have to worry about changing foods.
There is no real rule of thumb on amount. Depends on the pup. What did your breeder tell you about amount? Care to share who the breeder is and/or the sire and dam? Many of us are related by our Basenjis.