What I need to do if I forgot how many ms were on the finish

В этом случае ничего нельзя сделать, остаётся только переигрывать ран.

Maxlist, I just figured out what you can do. You can either use listdemo or write a cfg just like below for the timer during playback:

playdemo WGH-IL_1.dem bxt_hud_timer 1 bxt_timer_start

[Important: don't use playdemo in mid-run] (Important 2: I found out that the timer shows alternating times when you play it back more times.)

Or if you have splits, just edit it with notepad++ or Notepad, and find ms

It's possible to extract that information from the demos files alone, and most likely the mods are able to get that info for you.