The female plants starts wearing buds prior to flowering. The flowering timeline for marijuana varies by strain. The flowering happens as the function of light cycles, does not depend on size or age of the plant.
Before flowering, the plant undergoes vegetative phase of about 4-5 weeks where lighting is an 18/6 hour cycle.
Lighting cycle is the lighting ON-OFF duration under which the plant processes to grow into full bloom. For cannabis, it is mostly referred for Mimic Fall/Winter Lighting Condition, and flowering phase is of 12/12 hour cycle with reduction in lumen from 6500k to 2700k.
Using differential light zones, we are creating fall lighting conditions for Marijuana (fall flowering plant).