I wouldn't define it to a specific age because I don't think it works that way. Some people mature (mentally) sooner than others. It's about feeling comfortable in your own skin, and to consider the situation and the person you want to have sex with.
Your first time is a memory that you will have forever. That doesn't mean it needs to be planned out (more often than not, it doesn't turn out the way you thought) but it all depends on what you want.
These are the most important factors:
1. That you don't feel pressured into having sex. Sex should always be a mutual decision, through and through. DO NOT have sex just because your partner wants to.
2. Make sure YOU feel ready. Just because all your friends have had sex, or because they're all talking about it (for the record, a lot of people lie about having had sex) does not mean you automatically need to do it. Stay true to who YOU are.
3. Use protection. Always. Always. Always. I've worked with a lot of cases where the partner hasn't used protection and they've either gotten an STD (for the record, 1 in 3 people in the UK have Chlamydia) or have gotten pregnant. It's not worth the mental or physical hassle. Trust me on this one.
4. That you have sex with someone you can trust. I'm not gonna lie and say that you need to be in love with the person, because this is all very individual and you should make whatever choice you are comfortable with. However, make sure that this person will be there for you afterwards, will treat you with respect and that you can communicate. I've had plenty of friends that have met guys who only wanted to have sex and "pop a girl's cherry".
I would like to add that although I try my best to be as non-judgemental as possible, I would recommend that you be at least over 16 years old. Stay a kid as long as possible. You've got the rest of your life to have sex.
I would say there is no age to define when. Anywhere before high
school though in my opinion is just absolutely disgusting because you're
not even a teen yet let alone an adult.
But it would be stupid to just
tell a kid not to and that it is gross and they shouldn't do it cause in
the end they will do what they want. So if done just make sure you use
condoms, and if you can be on the pill/shot/implant.