You don't have to have a scope mounted on your rifle, in order to set the focus on the reticles but you should have the scope mounted on the rifle, in order to set the eye relief properly. Both have an optimum setting and that is what you want to strive for. Close should not be Good-Enough. ....
Keep in mind that your focus setting is good only to you and not the other guy. Once loaned a rifle to a buddy and expressly requested that he not change any setting. When I got it back, guess what?? ... YEP !!!
Oh yes, you can wear your normal glasses and don't forget to lock your locking ring.
Be Safe !!!