I think starting at day 6 gives plenty of time to 'clear' things out. As for the every second day or every day debate, meh. Tbh in the year and a half we've been TTC, I've heard both equally. I honestly don't think it would make a difference; the sperm will DEFINATELY survive 24 hours if you happen to O on a non-dtd day. I think the days you've got for dtd are great