Treating Basal Cell Carcinoma with Photodynamic therapy. How long should I wait before getting pregnant?

I have been told I have a small Basal Cell Carcinoma on my nose and my doctor wants to treat it with PDT. I have had PDT many times before with great success. I'm also currently in the middle of IVF - I have already had my eggs collected, but the embryo is not yet implanted - so I am currently NOT pregnant. My question is - how long after PDT can I get pregnant? (have my embryo implanted). I cant find any information about how long the ALA cream would stay in my system. Thanks