How big a batch do you make for a first time product?

When I have taken any classes in cold process soap, shampoo or lotions, the classes the handout always is in a large batch.  Since I have limited space I always like recipes in small batches.  And to tell you the truth, I am mathematically challenged so I wish some one could give me some simple tips on how to do that.  But in a recent post from Point of Interest, they have recently wrote on How big a batch do you make for a first time product? In this posting gives the authors suggestions on what she does but also calls out for any suggestions from her readers.  I will have to revisiting this posting for possible suggestions that may help me out.