The algorithm estimates the plucking point of guitar tones obtained with an undersaddle pickup. This problem is approached in the time domain by applying autocorrelation estimation. This work extends a recently developed algorithm and brings it to a practical and sufficiently robust level. Improvements have been made to the onset detection part of the algorithm. The algorithm also enables a new way to control, for example, audio effect parameters in real time by simply changing the plucking point. The paper discusses these issues and the real-time implementation in the Pd environment. In tests the real-time implementation achieved a 96 % hit rate while the estimation error remains smaller than one centimeter, except for a few outliers. Audio samples and a Pd implementation of the algorithm are available on-line at www.acoustics.hut.fi/demos/plucking-point/.