When should I harvest my plants?

Bit of a newbie question but I'm hoping someone can tell me how to know when to harvest a plant? Thanks in advance!

Check out theses links:
https://www.leafly.com/news/growing/time...g-cannabis
https://www.growweedeasy.com/harvest
https://www.royalqueenseeds.com/blog-kno...-plant-n84