We present an energetic model to describe the initial stage of growth of GaAs nanowire seeds in SiOx/Si (111) templates. The model explains the experimentally observed geometry of GaAs seed crystal emerging from Ga droplets in the holes, with either stepwise or ring geometry at the outer periphery of the holes and restricted by the steps that are much larger than monoatomic. Understanding and controlling this geometry is crucial for further growth of nanowires, improving their vertical yield and optimizing the morphology and crystal structure.