I buy frozen ones for lunch, I bake them at 350 for 30 minutes. If they aren’t frozen you could probably get away with less time. The best way would be to take their Internal temperature.
As for temperature and time, I overlooked the need to use convection, but boosting the temperature to 350 and giving it around another fifteen minutes baked it well...
I used to get frozen Chicken Cordon Bleu at GFS. I've not got any of it lately, so will have to look when I go there tomorrow or Friday. I wonder if it can be cooked successfully in a toaster oven, as my range is not hooked up now.