We present our ongoing research on automatic segmentation of motion gestures tracked by IMUs. We postulate that by recognizing gesture execution phases from motion data that we may be able to auto-delimit user gesture entries. We demonstrate that machine learning classifiers can be trained to recognize three distinct phases of gesture entry: the start, middle and end of a gesture motion. We further demonstrate that this type of classification can be done at the level of individual gestures. Furthermore, we describe how we captured a new data set for data exploration and discuss a tool we developed to allow manual annotations of gesture phase information. Initial results we obtained using the new data set annotated with our tool show a precision of 0.95 for recognition of the gesture phase and a precision of 0.93 for simultaneous recognition of the gesture phase and the gesture type.