What is the right age to introduce kids to our epics? Or it is not required at all to introduce them to mythology, considering the fact that we don't know it existed in reality or not?

IMHO, it's a very personal choice. You're not bound to introduce your kids to mythology if you wish. I know of one friend who got confused between Lord Ganesha and Lord Hanuman -- I haven't seen a more sorted out person then her. Probably putting facts as they are instead of asking kids to believe stories inculcates logic in them and they don't take things for granted. For example, the child might learn that unlike in epics, good doesn't always triumph over evil in real life. It also teaches her to believe in the self instead of putting her belief in an unseen force. Having said that, it's a personal choice and you have to make sure you're not hurting your beloved ones in the process :)

it is absolutely up to you, whether or not you want your kids to learn about the epics. in fact, i am just reading two books - Sita and Jaya by author Devdutt Pattanaik - a superb mythology writer. the books are a re-telling of the Ramayana and the Mahabharata, with a scientific and social twist to it. i am in fact planning to share it with my 10 year old as well. depending on your child's age, you can introduce some new retold versions that kids will enjoy also, mythology has nothing to do with religion, unless you choose to look at it that way. we are an atheist family, but these mythology retellings are more scientific and about social behaviour than about 'god'

Mythological stories, whether true or not is not important. What is the alternative? Fairy tales like cinderella,alladin, minnions,etc? Arent those fiction too? There are a lot of morals to learn from mythological tales so why not give your children an insight into them?Don't cut it out entirely.