When using ZynCal, the default time period in which a meeting can be scheduled is today plus 30 days. The link you include email will show all open space on your calendar for the next 30 days, for any available Calendar Hours after any meeting buffers you set have been removed from availability.
If you would like to offer availability for only certain hours in the date range or would like to offer a date range different than the default, the ZynBit Calendar pop-out is available for this purpose. The green ZynBit icon is displayed at the far top right side of the ZynCal settings page on app.zynbit.com.
When the icon is clicked, a screen similar to the following will display showing each meeting type you have configured and have not hidden.
To schedule a specific time range for the meeting, set the dates and times that will comprise the new range by clicking the purple clock icon in the meeting window. A screen with start and end dates and times will display.
Once the dates and times are set, click Copy Link for the new meeting offering to be copied into your buffer. You can then open your email and click paste to offer the meeting to your contact.