Answer:
When the solution turns clear, either at the end of the reaction or when you add sufficient cyclohexene
Step-by-step explanation:
The colour of bromine in the solution is usually yellow, however when the solution turns clear, this shows that all the bromine has been consumed.
Another way to make sure that all the bromine molecules are consumed is by addition of an unsaturated hydrocarbon like cyclohexene. Cyclohexene will consume the bromine molecules and the solution will become clear, while the cyclohexene becomes more saturated by becoming bromo cyclohexane.