Many tasks call for efficient user interaction under time delay-controlling space instruments, piloting remote aircraft and operating search and rescue robots. In this paper we identify an underexplored design opportunity for building robotic teleoperation user interfaces following an evaluation of operator performance during a time-delayed robotic arm block-stacking task in twenty-two participants. More delay resulted in greater operator hesitation and a decreased ratio of active to inactive input. This ratio can serve as a useful proxy for measuring an operator's ability to anticipate the outcome of their control inputs before receiving delayed visual feedback. High anticipatory input ratio (AIR) scores indicate times when robot operators enter commands before waiting for visual feedback. Low AIR scores highlight when operators must wait for visual feedback before continuing. We used this measurement to help us identify particular sub-tasks where operators would likely benefit from additional support.