Took two weeks of wearing them all day before my kenetrek hard scrabbles didn't hurt my feet anymore. Now I love them and they still get worn everyday, except now they fit great and don't hurt.
I waited a couple months before I started treating mine with the kenetrek boot wax. I recommend you just start waxing them right away and like most guys say, just put the miles on them now when it's not so critical, this way you know you can trust them not to leave your feet killing during a hunt.
I'd love to get a pair of the Mountain Extremes for late season. Also I'm not sure if you have tried Darn Tough socks yet, but they are awesome and can really make a difference with boot comfort. Made in the USA and come with a lifetime warranty.
Good luck, and just know that the pain and stiffness you are experiencing now seems to be norma