Installation Tips for Grouting
Here are several photos that show how much grout residue should remain during the installation.
This photo is after the grout was removed with the float and has been allowed to dry for about 15 minutes
You should use a slightly damp sponge and make 1 or 2 passes and remove most of the residue
This is after the 1-2 passes, and now it will be allowed to cure and will be cleaned with a damp sponge and then a dry cloth.