Start feeding two weeks into (auto)flowering?

Sometimes it says on the label how many weeks the soil lasts, 2 or 3 weeks seem common. You could start adding some, but not on every watering. Try to feed them with nutrients, then water alone (mayb with a little calmag), again only water, and again only water and then feed again. So F W W W F. Only water them when soil is dry and pot feels light. Sometimes that could take 20 days depending on the conditions. (A transplant also counts as a feed) Plants dont experience time the way we humans do, dont expect instant results. It could take like a week minimal for something to take effect, mayb longer. Leaves on the lower end tend to go yellow when they dont get enough light. The best advice that was given to me is leave them the fck alone :D