A simple analytical model is presented to describe the delay between flash- lamp initiation and laser- pulse onset in the flash- photolysis HF chemical laser. The predictions of the model agree well with experiments concerning the functional dependence of the delay on pressure, flashlamp intensity, optical cavity loss, and the absolute magnitude of the delay. The fractional photodissociation of MoF//6 is calculated for the experimental geometry used, the effects of flashlamp heating are considered, and a general expression for the temperature dependence of HF laser gain is derived and plotted.