How do I determine day 1 of my cycle? Hertility Support Team August 20, 2021 14:12 Updated Day 1 of your cycle is your first day of full bleeding before 5 pm. Related articles Do I test on a particular day of my cycle? How to take the test? Will my results be inaccurate if I collect my sample incorrectly? I’m struggling to fill the blood to the top line, what should I do? When should I return my sample? Comments 0 comments Please sign in to leave a comment.