I brewed my first porter almost a week ago. I never saw any bubbles. Today I opened it up to check the gravity. Its not quite low enough according to the chart on the kit that I used. Last time I used a kit, (an octoberfest) it started bubbling the next day. What can I do to get the gravity lower? The gravity reading right now is 1.02 it is supposed to be 1.012. Is this okay? What should I do next? 