From the WordPress Admin panel, go to: WooCommerce -> Time Slots
This sets the label that appears at the top of the dropdown box and timezone indication. You can change this to whatever you wish. (i.e. "Select an available time and day:")
Set the days of the week in which you want to make available for booking.
Set how many days out you would like Time Slots to make available. Example, if you set to 7, it will make time slots for the next 7 days, for the weekdays you've chosen, at the times you've set.
Set the amount of days to skip before making time slots available. This is set to 1 day by default, so Time Slots will create available times one day after the current day, which means that users would not see available times for the current day. Example, let's say today is Wednesday, and you've set the offset to 2 days. This would mean that the first available time slot would not be available until Friday (if you had Fridays enabled).
Select the number of available time slots that you want to create for each day. Set the number from the dropdown, then click "save changes" , and additional boxes will appear.
Set the times of the day you want to be available to calls.
Select your Time Zone.
Time slots has the functionality to clean up after itself. If you enable this setting, then upon deletion of the plugin, it will permanently remove all the database entries from your WordPress installation. Note, Deactivating the plugin does NOT remove anything if this setting is enabled, only if it is deleted. Only enable this if you plan on removing the plugin and not using it any longer.