New partner situation - how long before introducing?

Started seeing someone about 3 months ago. Things are getting pretty serious (like, she's met my parents serious). My kids are 11 and 13. They're with me 60% of the time.

I haven't mentioned her to anyone and my ex doesn't know. We're not at our house yet - we hang out at her place or go out. But like, how long is appropriate? Six months? A year? I don't want the kids to think I'm parading people through their lives, but also I don't want to hide this person I care about.

Anyone been through this? What's the actual timeline that doesn't traumatize everyone?