When would you carry out the development test for perming?

The development test for perming should be carried out before applying the perm solution to the entire head. This test involves applying the perm solution to a small section of hair to assess how the hair reacts to the chemicals, checking for any adverse effects or unexpected results. It's typically done 24-48 hours prior to the full perm application to ensure the hair can withstand the treatment and to evaluate the desired curl outcome.