The best age for this is when you like it and want to do it. Generally that starts around the age you hit puberty around 14-16.
The important thing is to be prepared and forget about readiness. No one can be 100% ready but everyone can be prepared for sex. The reason for this is to avoid certain issues associated with being intimate and with the sex act ie. Pregnancy and STDs.
So be prepared, read up, get familiar with your body, masturbate, explore yourself and understand what you want from sex. It is an awesome experience and really fun and addictive.
You need to find someone to have sex with and that person should be someone your trust and respect and will enjoy sharing your vulnerability with. Dont stress about age differences and legalities as long as you both are discreet and make sure you protect each other.
So for me and from my experience I would say 16years would be the age when you can start having sex.