The disk at the top of the pendulum (the twirly thing at the bottom of the clock) is used to adjust the speed of the clock. Unfortunately, this disk sometime seems a crude of a tool for such a delicate task. The disk usually has arrows on the top to remind you which way to turn it to speed the clock up or slow it down. However, unless you can read French the arrows may not help you. Just remember this: when looking down at the top of the disk, turning it clockwise will make the clock run slower; counter-clockwise will make it run faster.
How much you turn the disk when you first start to adjust to the speed of the clock is pretty much a guess. You may try a half-turn if the speed is really off. Then check the time in a half hour and see if you need to make an adjustment. Each time you make an adjustment to the disk, set the hands to the correct time. As your accuracy improves, your adjustments will become smaller and your intervals between checks will be come larger. If you go a week without making any adjustment, you are dialed in pretty tight. Any adjustments after this will be a hair's width.
Even though your clock may run for a year or more on one winding, wind it every two to three months instead. This will keep the tension on the main spring more consistent and will improve the clock's accuracy. I have a mini Schatz 400 day clock on my desk and I wind it very two months. At that time I also adjust the hands to the correct time and make a VERY small adjustment to the disk discussed above.
Remember that patience is the key to regulating an anniversary clock. Your reward will be a treasure that keeps pretty good time and that both young and old will enjoy watching.