Let's say you want to do a task this Monday at 10:00 am.
To do this you would use the do date to schedule the task for the day and add the time to the title of the task.
In the settings you can change the time formatting, but Marvin will understand all formats regardless.
It does not matter where in the title the time appears. Simply click the title and add the time. Most users prefer to have it at the start.