Hello friend,
I feel your pain with the purple/red trichromes...they're beautiful but make things a little difficult.
I think the best approach would be to look at others completed diaries for a rough idea of harvest. It seems many are between 9-15 weeks of growth. I would also watch for pistils changing, discoloration and shriveling. Some will harvest based on that, seeing about 80% change.
I think you'll also see trichrome changes closer to the end, yes you'll have reds...but you'll be able to see a milky cloudy quality versus the red glassy color they are now.
Watch your plants closely once you get to 9 weeks, and be wary of 1 plant being ready to harvest earlier than the others...i rarely have all the plants ready to chop the same day.
Happy flowering, love the beautiful colored leaves.✌️