You simply enter the times you want to be available into Tungle.  You can create a weekly template for this - for example if you are available Wednesday mornings between 9am and Noon and Thursday afternoons between 1 and 4pm.  You just need to tell Tungle once!  Of course, you can add daily exceptions for any holidays, etc.  Then Tungle blocks out any times you are busy based on your Google Calendar and when a client books an appointment through Tungle, it gets added into your Google Calendar. 

Quite simply - I'm a raving fan!