Warm or Hot Oil?

As someone who scrutinizes every word and trend in the language of cookbooks, I've been "stewing" (haha) lately over the following instruction:

• "In a skillet over medium-high heat, warm the oil. Add the onions and cook, 2 to 3 minutes, or until softened."
• "In a skillet over medium-high heat, heat the oil until hot. Add the onions and cook, 2 to 3 minutes, or until softened."
• "In a skillet over medium-high heat, heat the oil. Add the onions and cook, 2 to 3 minutes, or until softened."

I have my opinion, but which one do you find most accurate for cooking and most clear for the reader?