Knew I'd find it.

Zwar auf Deutsch.

The text by the circles says:

First shot - 10 minutes before the actual start: 5 blue discs (each disc is 1 minute).

Minute by minute, the blue discs gradually become red.

Second shot - 5 minutes have elapsed, still 5 minutes to the start: 5 red discs.

Signal one minute before the start: 9 minutes have elapsed, 1 minute still to go (against the picture with one red disc on the right).

Start! (yeah, that one is pretty self-explanatory :) ).

Hope that helps! There is the same page in English somewhere, but it was quicker for me to translate the German than to find it :)