agree with Iamthewalrus & Ida. there's probably no specific, numerical age that applies to everyone. it's that people develop in different ways and at different rates. so dating/romance doesn't even mean the same to all people at all ages. you do and feel different things based on where you are in life (school, friends, social relationships etc) and your experience with romance/affection.
if the two are 11 like with Iamthewalrus example, both factors are likely very early days, so it'll be awkward but on the bright side both people will learn a lot from mistakes. their general place in life will still be young but the other factor of dating will be higher, so they'll be better prepared to handle future challenges. it's kind of like developing any skill, really.
if both 14 like in zaL's example or 15-16 like with xXkf100Xx's example, they're a little more advanced as people (high school, has some independence and responsibility now) but not much more advanced in romance usually.
between 20-somethings, it varies wildly depending on how much they did at earlier ages. so I think early or late, everyone will have to figure out where they are in development relative to others and try to work through their feelings with more help (if underdeveloped) or be more of a leader if they're advanced and their partner needs it.
I also think as people age or develop in romance, the types of mistakes they make are very different, so it's hard to say anyone should avoid it at any particular age, since for example the embarrassment that comes at 12 can be replaced by shame about sex or identity at 16, and replaced by anxiety about lifelong commitments at 20.