I am about 10 days into P2 of my 2nd round, and I actually started (loading) on the exact day I got my period. I couldn't really find much info that it was a bad idea, and I really just didn't want to wait to start the round. I didn't really have any issues, and I got to eat a ton of food in my first two days that I usually crave during TOM. I felt like the first 2 days of TOM were also more intense, but then the last 2-3 days were very light. I don't think it did any harm with me, but if you do it listen to your body!