prism grout depth?

On the tile that we laid a bit ago, 7/16" thick. How deep should we clean the grout groves? Is thickness of tile enough? Or go down to CBU? Should you moisten the grove before grouting?

Thanks karl

Grout lines should be 3/4 of the way clean at the least and no need to moisten them what purpose would that serve

Tile should sit at least 24 hrs.