We study the fluorescence spectral dynamics of a molecule with two excited fluorescent states (called the precursor and product) within the stochastic point transition model, which includes a consistent description of the dynamics of the particles distribution in excited states and transitions between them. Crucial changes in spectral dynamics with increasing the transition rate between the precursor and the product are discovered. Analysis of the results of spectral dynamics modeling allows us to determine how the transition rate between the precursor and the product affects the isoemissive point in the spectra collected with an increasing time delay. The following main regularities were revealed: fluorescence spectra with a short delay not exceeding several solvent relaxation times (τL) may not pass through the isoemissive point; the isoemissive point shifts to the red with a decrease in reaction time constant (τeff). The shifted isoemissive point exists in the range 10τL<τeff<40τL. For faster reactions with 5τL<τeff<10τL, the isoemissive point blurs. When the reaction proceeds in the ultrafast regime τeff<5τL, the fluorescence spectrum shifts from a vicinity of the precursor spectrum to the product spectrum as a whole, changing its shape.