Endorsements

I have been reading about the different endorsements to get for tankers, hazmat etc. I have my CDL permit and as I have posted before I will start class in about a month from now. Do you have to have your license before you get your endorsements? or can I go to Motor Vehicles and take the written test for those now. I would like to be that much more valuable/employable in an employers eye while on the job search if I can. If it matters, State of North Carolina. Thanks guys and gals, you have been very helpful so far.