This plugin allows you to customize the text box. After click on them you see the window, where you can select the destination time.
Plugin breaks 24 hours to the minute with the desired interval.
It is possible to highlight certain time periods, i.e. available time or blocked intervals(for example: from 10:00 to 23:00, the discount is valid from 10:00 to 13:00. Buttons in time from 10:00 to 23:00 will be active, from 10:00 to 13:00 will be selected (default red))