Setup time

From TF2 Wiki

Setup time is the interval before a match starts. It consists of an initial period, usually quite short, in which players are added to the server and are able to choose their team, class and get their bearings, and a second, longer period (normally 30 seconds) which sets up the match itself. During setup, players are able to kill one another but points earned during setup time are discounted once the match begins. You can take advantage of setup time to check out the classes making up the enemy team and familiarise yourself with the map layout.

On most Control point maps, gates restrict players from moving into the main map area until setup time is over, though in some cases these can be bypassed using Rocket jumps or shot through.

Setup time is also a good opportunity for Soldiers and Demomen to damage themselves, allowing friendly Medics to get a headstart on their ÜberCharge meter. (Update: With the December 20, 2007 Patch, ÜberCharge builds up faster during setup time which is intended to make this unnecessary.)

Engineers use this time to set up their first Sentry guns and other buildings.