When the phase value is set to 180 it starts at the beginning, when the phase value is set to 0 it starts halfway in the oscillator.
I verified this with a freezable oscilloscope and a waveform of a pattern of different length pulses.
That would depend on where you define Origo to be in your graph. Apparently it is in the center, with the X-axis running from -180 through zero up to +180 (before wrapping around.) This is consistent with the Y-axis showing the signal having both positive and negative values