It depends on what direction you are coming in. My niece and her spouse are parking at Main Street parking on James Robertson for $25. I lucked out on Parking Lot A at stadium before tickets got expensive on secondary market. For safety supervised lot or garage may be best. Enjoy!
Also stay Off the interstate as much as possible on game day. Learn the secondary roads. My mother said the roads come into Nashville like spokes on wheel and it's true today.
For Titans games the state employee parking lots are available but Dec 30 is not a state holiday and I don't know if they will let fans park there before 5pm. There are also garages at court house, municipal auditorium and downtown library and I don't know if they will have empty spots, normally not too expensive.
Good Luck! Parking in Nashville sucks. I use to park at the clarion inn hotel parking because they never use to check for parking passes. However I married and don’t have my balls anymore so I’d never do that again. Just use the parking downtown and pay $40. It’s worth it.
Also, there are several parking garages around Lower Broadway, so if you choose to visit the bars and such before the game, it's a short walk over the pedestrian bridge that leads right to the stadium.
During Titans games I park in Lot E but neither E nor F were available for MCB. Parked in A during pandemic and it was nice and look forward to parking there Thursday.