Making the fact of adoption an ongoing part of family life from day one is the way to go, as others have so eloquently described. The "right moment" is now, however young the child. Sitting the child down when a bit older for a great revelation is definitely not the way to go.
There ae some lovely books for little children about adoption - here is one: www.bookdepository.com/book/9781934082065?redirected=true&selectCurrency=GBP&w=AFC7AU960PJG0TA8Z3D2&gclid=CjwKEAiA8K20BRDetNv3p6DNhXwSJADSwa3tygX10jH3poJ069MRt0D48TLCl8CDPV8SiHBVtFqQFRoCABPw_wcB
Just google "picture books abut adoption" and whole rafts of them will come up.
Congratulations on your new GS.
We have adopted children in our wider family and they have been welcomed by all, and treated just the same as all the others.
Support and friendship for those whose lives have been affected by estrangement.
Someone I know shouldn't be driving. In my opinion.


