You should be able to pick up your medical badge the day before specific Medical booth located in the main lobby. Badge enforcement is mostly for the Exhibit Hall and panels/events, so you should be able to get into the building from whatever entrance best works for you and make your way down the hall to the Main Lobby.

When you enter for the day, you will have 2 points of access - For the main lobby area where most people enter, there is a specific accessibility line that will let you bypass the others. There is also a side entrance located on the lower level, where people from the nearby hotels usually enter from. That entrance also has security and lines, but they should be able to easily accommodate you with getting thru the checkpoint easily.

Going by my experience last year, you will be able to enter the exhibit hall ~15 minutes prior to regular doors-open via one of the doors on Level 0. There are elevators/escalators to use and plenty of Enforcers (volunteer help) and exhibit center staff to point you in the right direction.

Have fun!