Waiting a week or two after a plant’s peak maturity to harvest isn’t the end of the world, the plant might just lose some THC. Busy schedules or too many plants to harvest and cause growers to delay harvesting plants for a little bit.
If you wait for a long time, several weeks or more, the plant will likely dry out and the buds shrink. The plant may start to rot and develop mold, especially in an outdoor environment and in cold climates.