Start times of appointments

Hello.

I'm trying to create a service within Bookings that has particular start and end times, and I'm struggling to reflect them in the service.

The service has 30 minute appointments, the first one at 10:15am, the last at 12:15pm. I've created the following settings:

Business hours - 10:15am - 12:45pm

Default duration - 30 minutes

No buffer (not required)

Time increments -  30 minutes

I was hoping to see the following appointments being available: 10:15am, 10:45am, 11:15am, 11:45am, 12:15pm. However, I can't seem to get the first appointment to be 10:15am, no matter what I change. This includes changing the business hours to 9:45am and setting a buffer of 30 minutes before the appointment. The first appointment is only on the hour or the half hour. Is there any way I can change the start time for a 30 minute appointment to quarter past or quarter to the hour? 

Sorry if there's an obvious solution, but I can't seem to find it. I've been at this for a while now, with my customer asking if they can go ahead and use this application.

Thanks in advance for any help/pointers, etc...