I took the class and applied for the TN HCP last June. It took right at 60 days to get the permit, but my guess is it will take a little longer now.
My advice is to make sure you get enough sleep the night before. We were at the range giving the class a total of 11 hours since my wife and I had to do the range qualification in different groups. There were four groups, me in the first, her in the last. The class part was 8 hours not including breaks. That is required by TN. The class just covers firearms safety and knowledge as well as the legalities of using deadly force. You will have to watch some goofy videos that are a bit boring. If you are a gun guy, most of the stuff is very basic info, and it may be easy to nod off and miss the good stuff telling you when you are legally able to use deadly force.
Shoot straight and take your time, although the firing qualifications are pretty easy. The written test is pretty basic as well. I don't know if they are the same for every class or not, but there was one question poorly worded that threw a bunch of people off in our class. No biggie, since 80 is passing on the test. It's a few hoops to jump through, but I'm glad we got it done with zero issue.