the making maker must at that zero point in time have been bigger than the embryonic multiverse, but by how much?
That assumes a materialist point of view, that the creator would be of the same substances (matter, energy, space, time) as the things created. When you accept that speaking of God in anthropomorphic terms as a metaphor catering the limitations of human understanding, you can recognize a creator who does not occupy space and time, the creator who made the space-time continuum, i.e. is the ultimate cause of its existence.