When to stay at new house?

[Msw1981]

My husband and I separated 6 months ago, he got a new girlfriend 9 weeks after separation after being together for 21 years. He moved in with her almost straight away. Our 2 boys aged 8 & 12 haven’t met the new girlfriend yet but we are planning on doing this soon.
At what point do I let the boys stay with her and their dad at her house? How quickly do I let things move?
the boys have zero interest in meeting her but I know it needs to happen.
thanks in advance.

Well to be honest it’s not really up to you now but if he’s working with you then I’d be asking to wait until they’ve been together 6 months for her to meet the children; if they weren’t living together then I’d say another 3 months for staying over but I don’t think you can do that for the sake of their relationship with their dad. How is he currently seeing them if he lives with her?