Last year was one of the stronger showers on record, with a peak of around 200 meteors per hour. This year astronomers are predicting a peak between 50 and 120 meteors per hour during the early hours of December 14th and 15th. Viewing for this shower is almost perfect because of the new moon on the 13th, meaning dark nights during the peak. Clouds will obscure any prime viewing, so you should check with the weather team often for updates as to potential cloud cover blocking the view as we get closer to the peak.
One way to think of a meteor shower is like a rain band. At the front edge, the amount of meteors seen will be very small. With the Geminids, one meteor per night will be seen starting on the night of the 6th. As the Earth's orbit crosses the path of the meteor stream, more meteors will be seen.
The peak of the showers, both meteorologically and astronomically, has the most action. This is when the meteors will be streaking across the sky at a rate of 1-2 per minute. Last year, a meteor was seen 3 times per minute.
After the shower peaks, the meteors will be less and less common until the 18th or so when we'll have passed completely through the meteor stream.
EarthSky has a great article with tips when watching the Geminid meteor shower.