You can use "Extra" time to open up extra availability for clients to book on a one-time, date-specific basis. This will create an available spot in your calendar outside of your “Regular Hours” when you would otherwise be unavailable. This is useful when you have an opening on a specific day, such as a half day or a holiday, but don't want this available block to repeat in future weeks.
To update your "Extra" time, navigate to your Availability tab from the left navigation. Select "Extra Time" from the center tabs.
From this page, you can click "Add Extra Hours" to choose specific dates and times when you are available.
Note: these will be one-off blocks, they will not recur on a weekly basis. To edit your Regular Hours, see this article.