I have draped over half round ceramic and steel forms. They require care as the form drains the heat from the centre of the glass while the outer edges gain heat. As I use only 1mm steel forms, the schedule works for both ceramic and steel. With your thicker steel, I would be more cautious up to about 500C than for the ceramic.
anyway what I do is 2 hours to 100C, soak for 10mins, 2hours to 300C, soak for 10 mins, 2 hours to 650C (or whatever target temperature you choose) soak for as long as necessary then anneal. You may want to slow down (ie., extend the time it takes to go up to 200C) as you have thicker metal than I do.