Reason why Kakashi could've had Kamui b4 shippuden

[Amaterasuice]

You know how Kakashi has sucky chakra reserves?
KAKASHI'S SHARINGAN IN PT1 PUT HIM BEDRIDDEN FOR DAYS. HE MAY HAVE NOT HAD ENOUGH CHAKRA TO ACTUALLY USE IT.

That is all.

 

[Sasuke..]

He has the headband...

 

[Lentz]

You must be registered for see images

 

[Prime Rib]

nope, and when you unlock MS even if you dont use, your eye goes blind after time even if you dont use, so if kakashi did unlock MS as people say when he kllled rin, that was over 17 years ago so even if he did not use, his sharingan eye would of been blind.