A short delay can be a documented feature on some models, but a new or changing delay should not be assumed normal. Check the instructions for the exact model rather than comparing it with a neighbour's disposer.
What the observation tells you
The useful distinction is between a consistent described start sequence and hesitation accompanied by humming, repeated button presses or a protection stop. Do not keep the control operated while waiting for an uncertain motor to start.
A useful next step
Record whether the delay has always been present and whether the appliance then runs normally. An undocumented change, especially with other symptoms, warrants assessment before further use.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.