Your natural lashes are constantly growing and the average individuals eyelash cycle is between 60-90 days. At the time of your first full set, your lashes will be at different stages of this cycle. 2-5 weeks after your first application some of the natural lashes will reach the end of their cycle and shed, taking the extension with them.
New lashes will then proceed to grow through as normal and at the touch-up appointment new extensions will be added to replace the extensions that have been lost.
The average time of an Eyelush touch-up appointment is 1-2 hours, depending on the number of lashes that have been lost.