Whitening before crowns and veneers is debatable
There are a few things to consider if you whiten before crowns and veneers. If porcelain will cover ALL teeth that show, there isn't much point, as the desired color can be prescribed to the lab.
If some natural teeth will show, they can be whitened and the final shade of porcelain can be chosen to match. But consider that ALL bleaching is temporary. In time, teeth will darken, perhaps only slightly. If the veneers are thin, this darkening will shine through and the veneers will protect the...