Putting the babies under her tonight would be best. Just always watch her reaction.
How old are the babies from the incubator?
I always put mine under my broody hens, when they are slightly wet so that they will dry completely under her.
But in my opinion tonight is best
BCP
The goslings will bond with the parent after it has been under her for about 2 hrs. The baby will get used to her voice and warm chest.
Hope This Helps
BCP