This is what we did...
Siliconed BEFORE grouting. All corners of room. All joints. Allowed to dry. Then grouted a week later.
Why a week later? Our tiler told me the adhesive needs to breath to go off. Air has to get to it and if you grout then its an airtight seal for still wet addy.
Check out (above) the corner of the room. What you can see are un-grouted large format porcelain tiles.
With a bead of Silicon already in place.
Also those holes have been drilled into the tiles to bring through electrical cable for a shaver socket and a cabinet light.
The tiles are being allowed to air dry for a week.
(As above - but with a bored wife waiting for her bathroom!)
Roll on seven years to today and the sink and cabinet are fitted.
The grout went in. And the wife was a bit happier !
** Here comes the advert bit !!
Oh and the holes for the cables (
closeup above) were drilled with a 30mm diamond core tile drill
specifically designed for drilling very hard porcelain tiles with the PORSADRILL
all in one tile drill kit for bathrooms.
One last point. Because the tiles were neutral, the grout was an off white so we used IVORY Silicon - not white.
That way we could get into the tiles and it didnt look glaringly obvious to be Silicon. It just blended with the grout.
http://www.365drills.com/jpgs/Silicon.jpg
Ivory Silicon let us blend in with grout !