Appeal to his self interest.
Like this:
Does he realize that if you wait that long, there's absolutely NO chance that Pup will be ready to hunt this fall? That if he takes him out, all that a post-July Pup will do is scare the birds?
Remind him that this is supposed to be his HUNTING dog, and does he not want to HUNT with him this fall???
And otherwise, remember my theory: men are Genetically Damaged, they're missing some chromosomes on the Y leg, and IT'S NOT THEIR FAULT they can't communicate decently.
And it's not your fault that you're Chemically Insane, either, especially on this issue! He has tweaked your Mommy Hormone with the puppy, and OF COURSE you're primed for that baby right this minute!
But it's still not his fault: remember the Damage...