We show for the first time, to our knowledge, that the buildup time to steady-state femtosecond pulses in a typical colliding-pulse mode-locked dye laser (lambda = 620 nm) with compensating prisms is 15 microsec after the pulses have been completely modulated. For a similar laser without the compensating prisms, the buildup time is 40 microsec and exhibits interesting oscillatory behavior in the initial stage.