This existed before on a Server called the Half Life Speedrun Server (which is down now) but I can't find it anywhere and the admin hasn't responded to anything in weeks.

Basically, all players are frozen for 5 seconds when the map starts to let everybody load in. Then the timer starts (can't be seen on screen) and when the first player reaches a certain point, e.g. the end of the level, it will display the time it took them in chat down to the millisecond. The best time is also saved along with the player name that set it and when someone beats it, chat will also say "New Record".

I assume you have to edit the maps in order for them to trigger the timer, I'll gladly do that myself if you tell me what exactly that trigger is. But if someone could write the actual timer script for me or could give me a beginner friendly instruction on how to do so, I would be endlessly thankful.