Spinodal instabilities and early development of density fluctuations are investigated in the stochastic extension of Walecka-type relativistic mean field including non-linear self-interactions of scalar mesons in the quantal framework. Calculations indicate that at low temperatures T = 0-2 MeV, the initial growth of density fluctuations and hence the initial condensation mechanism occur much faster in quantal calculations than those found in the semi-classical framework. However, at higher temperatures T = 4-5 MeV,semi-classical calculations provide a good approximation for quantal description. Calculations show that the typical size of initial condensation regions is not very sensitive to the temperature, but depends on the initial baryon density. These findings are consistent with previous investigations carried out in the non-relativistic approach with an effective Skyrme interaction.