No, they can scout your currently active war base as soon as war is declared..ie all through prep day.....including changes... you can even see cc filling, gives an idea of what troops, if you spot it...
Lots of clans allready switch bases just before war started, to throw opposition off....
Makes that easier...
Same for high lvl players, as soon as they shielded, switch to dummy base, then switch again, just before shield run out.... anti fluffy bunny measure...

