Switching Classes at the Beginning of the Game

I played a game where I selected Assault. Then, when two other teammates chose Assault I decided to switch off to something else. I elected to switch to Gunner. The game started and I spawned as Assault and had no access to the class switch menu via the V key. When I died I finally became a Gunner.

I dont think you can actually change class while you are alive

There is a 5 second window for you to switch your class before the game starts. The funny thing is that if you took too long to switch class others would see the icon over your head of the class you switched to and not the class you are.