Quick health check and should I start flushing?

Looking good. Great photos as well. With regards to flushing, you have a bit more to wait. How to know when your plants are ready: 1. Pistils: Your pistils are all white when should turn orange and start curling in. Pistils can be a bit misleading so not the best method 2. Trichomes: Get yourself a Jeweller's Loupe (at least x30 magnification) and check the trichomes on your buds. The trichomes on your leaves are decent but not as great of an indicator. The trichomes should have turned milky white. Now it depends on your preference, most people wait until 20% of the trichomes have turned amber, this is a good middle ground. If you want your effect to be more leaning to the light headed sativa effect, harvest before this point. If you prefer a more couch lock, indica effect, go for a bit more. I wouldn't go for much more amber trichomes because those THC trichomes would have degraded and turned into CBN (which is why you have a more couch lock effect). With regards to the actual flush, I have always flushed 10 to 14 days ahead of planned harvest date but many opt out of it and say it's a myth. My flush is usually the same amount of water I was given her during the last days but without any nutrients. Good Luck with the rest of your grow and enjoy the yield.