Biotin helps hair grow faster. But locks tend to go through a few stages. First they shrink considerably, because all of your hair is getting tangled and knotted into itself that the original length get compacted into a smaller space. Then they go through a phase where they seem to not grow at all. I'd guess this about where you're at right now. Then they start growing out of control.
My locks were a messy rat nest for about a year before they started coming together. They didn't seem to grow much. But after 6 years they have grown more than 15 inches. If you're at the year mark, you'll start seeing them grow really fast pretty soon. In the next few months they will probably grow 2-4 inches. And in 6 months, you'll see how quickly it happens. Be patient. Hair grows about 1/4 to 1/2 inch a month. But locks are in a constant state of tangling. So it might be as apparent right away. But soon enough, you will have locks longer than you ever expected. Then they might slow down a bit again. And then explode again. It's an ever changing process