If you have a brand new Polini, I would just install that sucker and run it as is. If, in the future you want more power, you'll at least have an idea if you did anything productive to your motor.
I for one am not a Hobbit owner, but definitely do all the math and calculations and try to be as accurate as my tools and ability will let me. I don't know if you're referring to Jennings books or Graham Bell's but personally I don't use Jennings' formulas because I disagree with his ideas on port/time area. I think Graham Bell's ideas are more practical and also easier to grasp.