When you see that the traps have already caught a considerable number of insects, it will be a clear indication that the trap has arrived. Time to remove them and change them for others. If the traps are hung on the plants rather than on them, this will be even more effective.
In the event that the crop is “clean", the adhesives will remain spotless, without any insects; But if you see that insects begin to appear stuck, it will be a clear indication that an infestation is starting; a time when you will also need to use a good insecticide.
Seeing what insect it is, you have the advantage of being able to purchase an insecticide product that is for that specific problem and You can also consult what is the appropriate procedure in that case. It is better to do it as soon as possible, since there is the possibility that some insecticides have certain deadlines that do not allow them to be applied when the harvest is approaching.