I think the lunch thing is a great idea. It gives you a specific time frame so if things don't go as smoothly as you'd like, neither of you feels like you "need to escape" or something because you know you'll be out of it in an hour and a half or less. Not to say that things would go badly, but I think having that schedule for a date is awesome because there's no confusion about whether or not to go to another place and keep hanging out or to go back to a certain person's house or anything. It'll be simple and straight forward, and you'll both have a lot of fun if you relax and just let whatever is going to happen, happen. Make the best of it and enjoy yourself. Don't sweat it too much!