Final answer:
The epilating strip should be removed before the wax dries completely to effectively remove hair without causing the wax to break.
Step-by-step explanation:
Lisa should remove the epilating strip before the wax dries completely to effectively remove hair from her client's face. Waiting until the wax has dried might lead to the wax becoming too brittle, which can cause it to break upon removal, potentially causing discomfort or incomplete hair removal. It's also important to ensure the wax has adhered to the hairs properly, which usually takes a few seconds after application before removing the strip with a swift pull against the direction of hair growth.