If you push the jump key at a time when it isn't legal to do a jump (such as after having used a midair dash already), you can still keep the key held down, and if you do, the jump will be executed at the first moment it becomes possible again (i.e. immediately after landing, or touching a pusher). Likewise, if you release and re-press the fire key for a weapon that isn't full auto, all before its attack delay interval has expired, you still get to fire the extra shot as soon as the delay wears off, assuming you're still holding the fire button at that time (only once per click, of course; otherwise fullauto would be a completely meaningless variable).
Waiting for the timer to expire in the respawn queue is different. If you jump the gun there and start holding a move button before the reentry timer runs out, then you'll spawn and stand completely still, until you press a different direction, or release and repress the one you're already holding. Likewise for clicking a fire button (even if you click once to express your desire to reenter the game, release, and make a separate click while the timer is still running--not that it's very useful to want to fire a weapon shot as soon as you spawn without looking around or changing direction). I don't know if this is a bug or not, but it makes sense that pressing a key "too early" when coming out of respawn should have the same behavior as pressing it "too early" for its action to legally be taken at any other time, at least for the main control keys like move, jump, shoot, and crouch.