Whether you actually see your dream sign or not, it doesn't really matter, IMHO. What matters is your state of mind at the moment when you realize you "see" your dream sign.

You can just say at anytime "oh wow, my dream sign" and get the real feeling of surprise when you RC.

This method worked for me when I was "surprised" at something strange happening. Nothing strange happened, but I told myself "wow, now that's strange". And then this feeling happened in my regular dream, promted me to RC and I got lucid.