This paper presents the results of how four dyads in an online task-based synchronous computer-mediated (TB-SCMC) interaction event use their agency to carry out speaking tasks, and how their choices and actions affect time spent interacting in the target language. A case study approach was employed to analyse the language functions and cognitive and social processing that occurred in audio recordings of spoken interaction between four dyads, alongside other indicators of pre-task behaviour, triangulated with results from learner questionnaires. The study revealed that whilst all cases engaged in overt spoken interaction, some cases also avoided the designed task and engaged in covert pre-task planning. Learners' ability to reconfigure 1) the time mode of the task design; 2) the ways in which technological tools were used and 3) language choice, all impacted on their time spent interacting in the target language. The findings highlight tensions between learners' choices across the three dimensions that they had reconfigured, raising questions as to how to support time in synchronous interaction in the target language whilst supporting learners' agency. The implications are presented and discussed.