How Much Time is Involved?
Schools approach robotics programs from different directions.  Most robotics programs are extra-curricular activities sponsored through after school programs.  A few schools, like Jessie Clark Middle School in Fayette County, provide a full time curriculum based course for their students.
A good starter robotics program would  be offered for 10 weeks, 1 day a week, for 1 to 2 hours a day.  This type of program would allow students to construct and program a robot following the LEGO Education format.   
To allow students the best opportunity to "Design, Construct & Program" their own robot, you would need to provide more time for the students.  Many robotics programs are offered for half the school year and provide practice times multiple days a week, multiple hours each day.