Sync vcita to your iCal through iCloud to pull busy time from your personal calendar, so you never get double booked when you have another event. 

Generate Your iCloud Calendar ICS Link

1. Login to your iCloud account at www.icloud.com using your Apple ID and click on Calendar.
   
   
    

2. Find your list of calendars on the left-hand side. Click on the Calendar Sharing Info icon next to the calendar you wish to sync with vcita.
3. Check the Public Calendar box, copy the subscription link, and click OK.
   
   

Sync to vcita

1. Next, log into your vcita account. 
2. Go to Settings > Staff (just Settings for non-admins).
3. Click the ⋮ icon next to the staff member you want to sync the iCloud calendar to and click Edit Staff Settings. 
4. Switch to the My Schedule tab. 
5. Click Sync Availability next to the iCloud option.  

6. Paste the subscription link in the text box and click Synchronize.

Synced events from your iCloud calendar will start appearing on your vcita calendar. They will have the prefix (Sync) in front of them.