The time of day isn't so important when using the 3x33 manifestation method. The key instead is consistency. You need a block of time to complete all 33 iterations of your affirmation without distraction or interruption. They should all happen in one session of writing. Mindfully focus on your affirmations and let them come onto the paper. While the specific time of day isn't important, you should write right around the same time each day. Set an alarm on your phone to remind yourself to sit down if necessary.