When can I celebrate on Facebook and not offend

Happy Birthday Luckygirl ?

You can celebrate now. Whilst many people are upset about today's news, it will probably not mean much to a child and their Birthday celebrations should not be put on hold.

I wouldn't worry about it; she could be very busy with no time to look at Facebook.

But that’s you floradora lots of us do especially birthday wishes, if the children or grandchildren are on Fb
I ve just had three family birthdays and posted wishes and photos on them all as they do on mine

It is my birthday today .... lots of good wishes on facebook.

I never post anything about my grand children on Facebook .

Well is it because everyone on FB appears in mourning for the queen
Ask her then do whatever they ask or want you to do

I personally don't think you've done anything wrong at all. Is your family in the same time zone as you - perhaps your post hasn't been seen yet? If your DiL has got upset about her son's grandmother wishing him a happy birthday, then I'd suggest that she needs to get out more! Just my opinion.
If it's really worrying you, then delete the post. Click on the “…” in the top right hand corner and you should see the delete option.

Probably a time difference thing, don’t worry about it, I’m sure your greetings were well received by your Grandson.