I soaked 2 vanilla beans in vodka for about 2 months, then poured the vodka in after 2 weeks of fermenting a porter. It worked out perfectly.
This is almost exactly how to make vanilla extract. Splitting and scraping the bean putting it all in the vodka or I use Rum, and shaking up a bit now and then.
I recomend you get beans in bulk online, Amazon has some not bad prices for grade b beans in bulk for 1/4 to 1/2 pounds. The only diffrence between grade b and grade a is how pretty the bean is. They make extract from grade b beans, commercially.
But your bean choice is fine. I recomend for a gallon that you use 2-3 beans and just let it sit in the secondary for a good couple of months. It takes 2 months for a true extract using 35% ABV alcohol, your secondary should be around 10% to 12% so 2 months would be good, just split and scrape into it. If the pod isn't at least split then the alcohol can't get to the good stuff as easily.
I make several cups of vanilla extract at a time. 6 beans to a cup of vodka or rum, and the best part is you can use the same beans for a second batch.
Matrix