The time distribution of quantum events

We develop a general theory of the time distribution quantum events, applicable to large class problems such as arrival time, dwell and tunneling time. A stopwatch ticks until an awaited event is detected, at which stops. The represented by projection operator $\pi$, while ideal modeled series projective measurements state gets projected with either $\bar{\pi}=1-\pi$ (when does not happen) or $\pi$ eventually happens). In approximation in $\delta t$ between subsequent sufficiently small (but zero!), we find fairly simple formula for ${\cal P}(t)$, representing probability density that will be detected $t$.