Automated writing evaluation tools have been shown to improve writing quality. However, the impact of automated feedback, and especially the timing of the feedback, on students’ writing process is still unknown. Hence, we analyzed how feedback timing influences the revision process. Three experimental conditions were implemented into the writing tool CyWrite: no feedback, immediate feedback during the drafting and revision stage, and feedback during the revision stage only. Keystroke data were collected from 60 ESL students while conducting a source-based argumentative writing task. The revisions made during the writing process and the students’ satisfaction with the system were analyzed. The results showed little differences in the amount, size, and duration of revisions between the three conditions. However, students reported they felt more disrupted when feedback was provided during the full writing process rather than in the revision stage only.