work as a massage therapist- I have a waiting list of clients and when i get a cancellation and free slot is there a way to reserve it and then offer it out to those wanting to scheadule in a session??

at the moment its quite long winded- changing my availability to block it out for all client base to find,  then emailing clients on waiting list, waiting for response and then manually sheaduling or resheaduling them. 

I know some purpose built salon softwares do this- fresha, timely- but Im so used to calendly now as are my clients Im not keen to change

thanks all