Depende. If they ask something, I'll explain it in a way na appropriate para sa age nila. Siguro sa ibang bagay as they grow older na, like bodily changes. Any time is ok, malaki ang saklaw ng sex, not just the act itself but consent, how to take care of yourself, how to be safe, how to say no, how to establish boundaries, etc. You can teach them sex ed without talking about the sexual act, depende naman sa age and maturity nila.