"mamaivamsho jivaloke jivabhutah sanatanah" (Gita 15.7)
This verse of the Gita also states that the soul is eternal. If someone ask you, "Since when you have existed?" the straightforward reply is, "Ever since god existed." And if you are asked, "How long has god existed?" the reply is, "Ever since I have." And if you are asked, "Since when you and god existed?" the straightforward answer will be, "Since the time when even ‘when’ did not exist." This means that ‘time’ came to existence after god and us, and as such cannot be used as a frame of reference to determine our beginning. That is to say, we are all eternal.