In your opinion, when do you think is the earliest age that is okay to start dating?
The term "dating" means you are taking a person out on a schedule appointment, such as to dinner or a movie. We use it far too loosely these days. With these days of the Internet, people claim to be dating simply because they like someone and they want to claim the relationship is exclusive. Yet, people are claiming to date when they never actually been in each others physical presence, let alone go some place together.
What really happens is that people are limiting their options before they really know another person. Dating is about getting to a person by spending time with them. There is nothing about going on a date with someone that requires a commitment, beyond wanting to spend time with another person.
Along with this, I've seen people treating "dating" as a term for being friends with sexual rights to each other. Sex belongs only in marriage (Hebrews 13:4). Sex before marriage almost always messes up a relationship.
When you are looking for someone whom you may eventually want to marry, then that is a good time to consider dating. That process can take several years. Dating is a chance to get to know a person better than just by casual conversation. So if you don't have someone you are interested in getting to know better, then you aren't ready to date. Generally it is the male who asks and it is expected that the male pays for whatever is done. The reason in the past is that this proves to the woman that you are able to support her if you do ever marry. If you can't afford to buy someone else a movie ticket or a dinner, then it is too soon to date.
Dating too soon can lead to problem. You may find yourself bored and look for entertainment in inappropriate ways. You might have problems with self-control. So a part of the answer is how mature and responsible a person is. Often that has more to do with a person's character than his age.