The time needed from the moment you launched the game (clicked on the .exe) to the moment you entered the server (to the map view) with all assets 100% loaded was about 1 second. Literally! You click the icon on your desktop and BAM! you're already on the server and you can start shooting. But that was written by John Carmack in C :-)
From other examples - I have a "ModRetro Chromatic" at home which is simply an FPGA version of the Nintendo Game Boy. On this device, you don't see the falling "Nintendo" text with the iconic sound known from normal Game Boys. When I insert a cartridge and flip the Power switch, I'm in the game INSTANTLY. There's simply absolute zero delay here. You turn it on and you're in the game, literally just like with that Quake.
For comparison - I also have a Steam Deck, whose boot time is so long that I sometimes finish my business on the toilet before it even starts up. The difference is simply colossal between what I remember from the old days and what we have today. On old Windows 2000, everything seemed lighter than on modern machines. I really miss that.