Oscars are funny creatures, once they get older they will let you know when they are hungry and unlike most fish they dont, in my experience, eat to the point of stuffing themselves. I feed mine once a day but feed the amount on what he "tells" me, if I pick up the bag and he swims up to the top I feed him, I also feed him based on how active he is when he comes up, if he is very excited I feed him more, if he comes up but doesnt act to interested I feed him less. I have never used any exact number of pellets and it has worked for me through the years. What is fascinating is he will recognize the Hikari cichlid pellet bag, if I pick up the algae wafers for the pleco he will ignore it but when I pick up his food he comes up to the top. They will also get upset and sulk at the bottom of the tank for a few hours. One word of warning, stay away from store bought feeder fish, they tend to carry diseases and parasites that can be transferred to the Oscar. I have tried many different food items and the only thing mine will eat is hikari cichlid gold floating pellets and frozen brine shimp/blood worms (not thawed), even when offered live feeder fish, that I bred and raised, he ignored them totally.
Also I am not going to preach about it since yours is still small and I dont know what size your tank is but a single oscar will require a 55G tank minimum.