Hey Growmie, Most Growers switch to the flowering stage as soon as the plant has established a solid root system. In optimal conditions, plants should be kept in their vegetative stage for approximately 60 days. This time period should give the plant the opportunity to maximize yield and acclimatize to growing conditions. Another way to see it is Ideally, you want the plant to finish at approximately 24 to 36 inches tall, so you will induce flowering when plants are approximately 12 to 18 inches tall. Hopefully, I answered your question and remember Happy Growing and Free your mind one puff at a time.