New girlfriend wanting to meet the kids already

Been dating my girlfriend for 3 months and she's already asking to come pick up my kids with me. I don't think it's the right time yet but she keeps saying I'm keeping her hidden and it makes things weird. My ex will lose her mind if she sees this. With my kids it's complicated because my son is still pretty angry about the divorce and I don't want to throw another change at him yet. How long did everyone else wait before introducing new partners to their kids?