I used to play Doom with keyboard only. Right hand on the arrow keys, while the left hand shot with Ctrl, ran with Shift, activated with Space and toggled strafing with Alt. I even played Descent with the arrow keys. It took me hours to get the perfect keybindings for that one down. I think I flew up and down with A and Z.
Jedi Knight was the first game I played with mouselook. Not with WASD, but with the numpad. I thought I was a genius for discovering that. I put my main force powers around that and probably switched weapons with the mouse wheel.
Can’t remember when I switched to WASD. Probably around Unreal or Half Life.