This study addresses the effects of the timing of explicit instruction within the three phases of a task cycle (pretask, task, posttask) while considering learner's previous knowledge. Eight intact groups (N = 165) of French L2 university-level students (4 B1- and 4 B2-level groups) completed two tasks. Groups were formed according to previous knowledge. Three groups received explicit instruction on the French subjunctive during the pretask, task, or posttask phase of each task. The control groups completed the task without prior instruction. Participants completed an elicited imitation test and a grammaticality judgment test as pretests, immediate posttests, and delayed posttests. Results showed that explicit instruction embedded in a task facilitates the development of explicit and implicit knowledge and that the efficacy of instruction is not significantly influenced by the timing at which it is provided or by the learners' level of previous knowledge.