  We reformulate the time-dependent Gutzwiller approximation by M. Schir\'o and
M. Fabrizio [Phys. Rev. Lett. 105, 076401 (2010)] in the framework of
slave-boson mean-field theory, which is used to investigate the dynamical Mott
transition of the generic two-band Hubbard model at half filling upon an
interaction quench. Interorbital fluctuations lead to notable changes with
respect to the single-band case. The singular dynamical transition is replaced
by a broad regime of long-lived fluctuations between metallic and insulating
states, accompanied by intriguing precursor behavior. A mapping to a spin model
proves helpful to analyze the different regions in terms of the evolution of an
Ising-like order parameter. Contrary to the static case, singlet occupations
remain vital in the Mott-insulating regime with finite Hund's exchange.
