Talked with my mother-in-law last night and she preheats her pan. I think you can achieve success either way. Recipe from Joy follows:
Oven to 450, rack in center.
In large bowl, mix together:
1 cup AP flour
1/2 tsp. salt
In another bowl, whisk:
2 large eggs
1.25 cups milk
Fold liquid into dry ingredients. A few lumps are okay.
Grease popover tin. Fill cups 2/3 to 3/4 full.
15 minutes at 450, then reduce temp to 350 and bake 20 more minutes. DO NOT OPEN OVEN during cooking.
Unmold and puncture sides with knife to let steam escape.
Alton's recipe is probably worth a Google.
This post was edited on 1/1 at 7:08 am