Place the jar in a cool, dark place for 2 months, occasionally agitating the beans in the alcohol.
When the extract is done, you can leave the beans in or remove them.
Some say to split the vanilla beans in half lengthwise before submerging and others say to submerge the vanilla bean whole for the extraction process. It doesn’t seem to affect the final outcome, so I say do whatever is easier for you.
Make Vanilla Extract Faster. I haven’t tested this myself, but I’ve read that you can cut the vanilla beans in half, or even smaller, and that you’ll make extract in as little as 3 weeks. I usually aim for about 2 months for my vanilla extract, but the longer you let it sit, the more the flavor develops.