Magnetoelectric multiferroics promise direct cross-control between coexisting ferroelectric and ferromagnetic orders, which is of interest for applications in magnetism and spintronics. A particularly interesting type of cross-control is found in spin-spiral multiferroic Mn2 GeO4 , where a ferroelectric multi-domain distribution can be globally inverted by a single magnetic field sweep. In this work we show that this repeatable cross-control is not obtained immediately after entering the multiferroic phase. Instead, zero-field cooling produces a metastable multidomain state in which polarization, magnetization, and antiferromagnetic order do not yet minimize the trilinear magnetoelectric coupling. Using optical second-harmonic generation for ferroelectric domain imaging, we demonstrate that a single field cycle deterministically drives the system from the initial metastable state into an equilibrium domain configuration that shows repeatable domain inter-conversion. This initialization behavior originates from a deterministic pathway from metastable to equilibrium domain patterns, in contrast to the more common – and less reliable – stochastic domain ”training” procedures that require repeated field cycles. Understanding the initial domain evolution thus enables reliable cross-control in magnetoelectric devices with highly interlinked order parameters.