Ditto. Though I think IrishLass includes hers from the beginning.
Deanna, I hear you. If I ever start making a bunch of batches of shaving soap, I'm going to have Popeye arms.
You can pretty much add it any time you want during the soap making process. That said, I usually add it at the end of the cook right before I want to put the soap into a mold or whatever. The added liquid makes the soap a little softer and easier to scrape out of the soap pot. The downside is it does take some arm power to blend it in well.