Time-resolved self-bias voltage measurements and spatiotemporal resolved optical emission spectroscopy were used in order to monitor particle formation and instabilities in the initial stage of 13.56 MHz SiH4/H2. The effect of total gas pressure on the particles formation and the time required for the plasma to reach steady state was investigated. Both techniques were very sensitive in monitoring the nucleation and coagulation phase of particles formation. The characteristic times required for reaching steady state were similar for both techniques indicating that electrical properties and chemical kinetics are affected in a similar way from particle formation. The increase of pressure resulted in a significant shortening of the instability period and this can be a significant advantage in the deposition of device grade silicon thin films.