Below is a general guide to the frying temperatures for various types of food using olive oil
Medium Temperature, 266-293F - The best type of food fried at this temperature is food with a high water content, like vegetables, potatoes and fruit
Hot Temperature, 311-338F - Food covered in batter, flour or breadcrumbs are good in fried at this temperature.
Very Hot Temperature, 347-375F - Small, quickly fried foods, like small fish and foods like croquettes, or "croquetas."
You can try using the T-Fal Pan it has an indicator that when the light turns red the pan is ready to use.
Hope this helps