Instrumentation is a valuable technique to gain insight into a program's behavior. Safety-critical real-time embedded applications are time sensitive and so instrumentation techniques for this domain must especially consider timing. This work establishes the basis for measuring the effectiveness of approaches for time-aware instrumentation in addition to coverage. We define the ETP shift effectiveness metric and define its optimality criterion. We identify locations in the program where program transformation techniques can be applied to increase the instrumentability of the program. We subsequently use the proposed metric to evaluate two transformation methods that improve the effectiveness and coverage of current techniques for time-aware instrumentation by a factor of five.