I have had a pair together in a breeding cage for 3 weeks. There is no sign that the hen has even been in the nesting box yet. Her cere is a really dark chocolatey brown, darking than some of my others that have already laid eggs.

How long do I leave them together when nothing is happening?

This is a photo of her, not a very good close up of her cere.

Thats long enough to know she isnt interested. I would put her back in the aviary.