In my opinion you should not candle every day. There are several reasons, but I'll focus on the most important...you have a very fragile embryo trying to grow in there.
It is best to wait to candle until day 7 on white & brown eggs.  Colored and very dark eggs, I wait until day 10.  You really can't see much in there before then.  On white eggs is an exception and you can see growth (vein networks) fairly early.  I discourage candling in the first week though, as this is when some of the most vital embryo development initiates.  
Another thing to remember during candling is very gentle handling.  Never turn the egg to try to get a better look.  This can cause problems with the embryo getting twisted up in the vein network and cause it to perish.  During candling, simply lift the egg gently to the light source, get a quick look to identify growth and place it back in its warm incubator as soon as possible. 
I know how exciting it is to see if something is happening, but patience will pay off if you wait until you can clearly see something.  Excessive handling is just a bad idea during incubation, which really requires a steady, stabile environment for successful hatches.  jmho
Jody