There is a growing interest in accurately measuring the timing of the J peak of the ballistocardiogram (BCG) in order to obtain cardiovascular function markers non-invasively, especially in modern home healthcare applications. In this paper we have studied the effect that some common uncertainty sources have in the time measurement of the J peak. This is a necessary step towards the standardization of modern ballistocardiography systems equivalent to that available for ECG systems. We conclude that, to reduce J peak time uncertainty below the measured intrinsic uncertainty of about ±2 ms, the minimal bandwidth should be from 1.5 Hz to 22.5 Hz; the sampling frequency can be decreased up to 50 Hz when using cubic spline interpolation; 5 bits are required to quantify the signal, and signal-to-noise ratio (SNR) and signal-to-interference ratio (SIR) should be over 40 dB and 3 dB respectively.