When to harvest? Plant is 53 days from seed (week ...

Looks too young to harvest to me. I'd wait until you start seeing yellowing of the leaves, that's a good indicator of being ready to harvest. Also, a Loupe/Magnifier would be helpful to check the trichomes. Once you start seeing Amber trichomes, go for it regardless of the coloring on the leaves.

She looks ready to me but the best way to check THC colors, you may want to check buds with magnify glass 10% amber 90% milky is best.

First nice plant !! The best way to check when to harvest is to buy a cheap magnifier and look at the resin. They change from clear to milky and then brown as they age, peak time is when most are milky. You can harvest earlier for a more speedy head high or later for more couch lock high, but that comes down to personal choice. Most times given are for perfect growing conditions which i use more as a guide. Hope this helps !!👍