First-my disclaimer- making soap is inherently dangerous due to the use of lye. If you are not willing to assume the risk involved, please do not attempt to make it.
Natural soap takes a minimum of 4 weeks to cure- so, even though you can make the soap before the due date (it only takes a few hours), it will need a bit of time before you can use it.
If you haven't made soap before, check out my tutorial for instructions, and an easy recipe: http://barsoapnatural.com/how-to-make-so…
If you're going to make soap using a liquid other than water in your lye solution- you're going to want a couple extra instructions.
When water is mixed with lye, the solution heats up quite quickly to approx. 180 degrees. When other liquids, such as juice, beer, etc, that naturally contain sugar are mixed with lye, the solution gets even hotter. This often leads to what is known as a "Lye Volcano," where the mixture foams and bubbles and rises, sometimes quite high, in your container. You do not want to have ANY contact with lye solutions.
For this reason, when I make lye solutions with anything other than water, I ALWAYS USE A VERY DEEP CONTAINER- think 3 gallon bucket-- Even if your lye solution is only 2" deep in the container, I would still recommended going this route. This is for your own protection. I mix lye solutions on my porch, rather than inside, and I stand back, using a VERY LONG handled spoon to stir the solution until the foaming and initial steam release goes away. Once the heat is released, the foaming will dye down, and you're past the scary part!
Then, it's business as usual. Wait for the solution to cool. Wait for your oils (melted in the microwave) to cool. Follow the rest of the tutorial's instructions.
An additional step you can take to minimize the risk of the Lye Volcano, is to freeze your juice before using it, or at least get it to a slushy/icy state. Put the frozen liquid into your deep container. Sprinkle the...