Most annual flowering plants die from the top down. That means they yellow from the top not the bottom.
Leaves are going to go yellow and die eventually. Cannabis is an annual flowering plant meaning it grows, flowers, produces seeds, and dies. The seeds start that process again. But because its flowering is also triggered by photoperiod it can be kept growing for years by manipulating the light hours to prevent it from flowering as is possible with thousands of other plants.
The leaves will yellow naturally on their own even if you're still feeding them up until the end because the plant is coming to the end of it's life cycle.
All too often what you see are plants weeks out from being done with yellow leaves that lack chlorophyll and are unable to produce the energy the flowers need to reach their full potential. That's caused by growers that switch to flower and seem obsessed with no N and more P/K. Then they start flushing weeks before the plant is close to being ready to harvest. The entire plant still needs nitrogen even in flower as it needs P/K. It's needed for too many plant functions to list. Yet right when those functions are the most important the plant is deprived by a nutrient it needs. It's like people are trying to make their plants leaves turn yellow.
Here's some examples of what I mean.
These plants were grown outside in 3 gallon pots of soil which are small to begin with. They were fed only a couple times with the rest of the watering being straight from the hose. They still had about 4 weeks left yet all the leaves are yellow from lack of nitrogen plus other nutrients. I have no doubt that had these plants been fed properly they would have produced 25 - 35% more bud by weight.
Here's some plants fed until the end. The leaves are yellowing because the plants are coming to the end of their life cycle. The leaves are yellowing more at the top than the bottom. Nitrogen is a mobile nutrient so if those leaves needed the nitrogen they would take it and the bottom leaves would go yellow first. As with most flowering annual plants the flowers will die off before all of the foliage. The plant will stop taking nitrogen when it doesn't need it anymore.
If you feed properly the plant will yellow on it's own when it's time. There is no need to force it. If you don't overfeed you'll always have healthy plants that will change on their own based on what stage they are in their lifecycle.
