There are two ways Zenbooker can determine you business's availability: Based on Team Availability (default), and Manual.
How it works: Based on Team Availability
If you have 2 service providers who are available to work at 8 AM on Tuesdays, and a customer books a job for 8 AM on a Tuesday -- until you assign this job to one or both of your available providers -- you will still have 2 spots bookable for 8 AM.
If you assign this job to one of your providers, then you will now have one spot left for 8 AM.
If you assign this job to both providers, you will have 0 spots available at 8 AM.
Additionally, let's say the job's duration is 3 hours, that means Zenbooker will also block off all time slots between 8 AM and 11 AM.
In short, the key thing to know when using the team availability option: jobs don't affect your team's availability until they are assigned to at least one service provider.
How it works: Manually Setting Availability
If you don't want Zenbooker to take into account the number of service providers you have available at any given moment, or you don't feel like adding all of your service providers and their employee hours to Zenbooker, you can set your Availability Policy to Manual, which simply lets you set the max number of jobs that can concurrently take place before a time slot should become unavailable.
For example if you set your limit at 2 jobs, and you have a 2-hour long job scheduled at 8 AM and another 2-hour job scheduled at 9 AM, your available slots would look like this:
8 AM - available // since 1 job overlap this slot
9 AM - unavailable // since 2 jobs overlap this slot
10 AM - available // since 1 job overlap this slot
Changing your Availability Policy
Go to Settings > Scheduling Policies, and scroll down to the section called Availability Policy, and select which method you'd like to use to calculate availability.
If you use Based on Team Availability, it's important to make sure all your employees who will be performing services are added to your Zenbooker account as Service Providers and that their employee work hours are accurate, as this is what's used to determine the base number of service providers available at any given moment on a particular day.
To view or make changes to an employee's work hours, go to the Team view from your Zenbooker dashboard and click on a service provider to see their work hours.
Under Availability, you can adjust the provider's hours and days available.