When scheduling a job, you have the ability to set an arrival window. This will be the time frame your customers can expect you to arrive for the job. You can choose to have this window be set as the default for all jobs or set it on a per job basis.
To set the arrival window, create a job as you normally would. When you're setting the schedule time for the job, you'll see an 'option' bar at the top of the calendar. Select 'arrival window.'
Choose the amount of time you would like to give. It can be none (this will give the customer an exact time) or as large as four hours. If you want this window to applied to every scheduled job moving forward, hit 'Set arrival window as default' in the bottom left. Then hit 'done' to save this setting.
The window will begin at the time the job is entered into the calendar. So if the job is set for 12:00 pm and an arrival window of two hours is selected, the arrival window will be from 12:00 pm-2:00 pm.
The preview of the text notification that your customer will receive will adjust as the window is changed.