There are two different ways that you can set this up.
Click 'My Apps' along the top of your screen and then GET MORE APPS:
Once on the apps page, click the clock icon on the right side of the screen.
You can then choose what you would like the soonest availability to be by clicking the desired option. For example, if you choose '2 days out' a customer will not see any Online Booking Windows sooner than 2 days from the day they are making their booking.
2. From your dashboard, click the circle icon in the upper righthand corner and then 'Account settings'
From your Account settings, click on the 'Business hours' option
From there, you'll be able to set the soonest availability
Learn more about why online booking is right for your business.