Letrozole/femara effects?

I'm on day 4 of 5 in my first round of letrozole- just wondering if it makes you ovulate earlier than normal and if it effects CM at all? I have been getting very clear fertile CM the last few months and I wonder if it will throw it off? I will star OPKs the morning after I'm done with the pills to be sure I don't miss ovulation just curious what other people have found? Success stories? Would love to hear them :)