Some further information that may be of interest.

When you have the settings mentioned above running, it is still not actually instant respawn as regards you will still get the freeze time and cam before you respawn which is about 6 seconds from when you die till when you respawn.

There is a way around this though without having to use an instant respawn plugin.

The cvar that deals with this freeze time is spec_freeze_time which is a cheat cvar.

If you use Sourcemod, you can easily hook this one cvar by adding it to your sourcemod.cfg like this

sm_cvar spec_freeze_time 2

Just change the value to as you wish. The setting example above will give you a freeze cam when you die and you will respawn 2 seconds after you die.

You would still need to use the other cvars in your server.cfg as regards

mp_respawnwavetime 0
mp_disable_respawn_times 1

This is how you can achieve True Fast respawns without specific instant respawn plugins.
sm_playsndsgc vo\announcer_am_killstreak07.wav
nav files
sv_cheats 1
nav_quicksave 0
bot
go spec and type nav_generate and wait