I don't have experience with the Earthborn lines of kibble, but I know that at one point Burton's litter mates were eating upwards of 6 cups of Pro Plan Sport 30/20 (however, I think at that point the males eating that much were between 80 and 90 lbs). So I think the recommended amount for Tucker might actually be on par. I would suggest you just watch your pup's figure and feed that way. You could feed what the bag recommends and if Tucker looks thin, up the amount, if Tucker looks pudgy, cut back a bit. It really depends on the dog (how active is he? is he intact? metabolism? lifestyle? stuff like that). You could start transitioning your pup right now to an adult or all life stages food if you'd like.
Any chance you could talk to your breeder to see where the litter mates are at? Mine would send me updates when they needed an increase or decrease in food.