The tradition of "Tfillah k'vasikin" is to daven at the first minute possible.
There are a lot of minyanim going on at the same time at the Kotel. The signal for everyone to start davening in unison is Reb Yossel Wienbergs unique nusach in which he shouts out "Kumah" as a signal for every one to start davening,
This was filmed by Oorah volunteers at their annual "Nesiah" to Israel with Reb Chaim Mintz.
