I am starting a 12 week regimen of 500mg of Testosterone Enanthate followed by 2 weeks off then a post cycle of Nolvadex. I also bought Letrozole as it was suggested to have incase my nipples get sensitive during the cycle. My question is should I use the Letrozole straight away just to be on the safe side or only if I start experiencing issues? Is there any downside to using it during the cycle? Thank you for your response.