Hi there, I agree with m0use about taking pictures in a better light, it's a little hard to tell the trichome color in a yellow light. As for flushing, as long as you are using organic soil, there really is no reason to flush. Flushing is to remove any build up of salts in the soil so the plant can properly take up nutrients.
I've heard a lot of people flushing to gain color, but the only thing that does is make colors of the plants literally eating itself alive (its not that pretty) but strains that HAVE color will make color flush or no flush. Also cooler temperatures are what makes the colors show as well, so if that's what your goal is, put an AC in with room, or make the temp cooler for the last going off!
If color isn't what your after, and you have used some hydro nutrients along your grow, then test the run off and make sure it's got the proper amount for end flower, and if you feel like there would be a salt build up, or your plants look unhappy, then maybe consider a flush, but your flowers look really nice so I don't think it's necessary.
If you are looking for a body stone: harvest when there are a few amber trichomes, and then by the time it's dried and cured it will process more amber. It's looking really plump and basically ready to harvest like you mentioned, so just consider the trichomes and make sure it's going to give you the smoke you want! 😉
Good luck on the grow!!