Although we have little knowledge of the Universe before the Planck time, only speculation, we can calculate when this era ends and when our physics begins. The hot Big Bang model, together with the ideas of modern particle physics, provides a sound framework for sensible speculation back to the Planck era. This occurs when the Universe is at the Planck scale in its expansion. So one can only measure the size of the Universe much like you measure the radius of the Earth. The Universe expands from the moment of the Big Bang, but until the Universe reaches the size of the Planck scale, there is no time or space.
Time remains undefined, space is compactified.
During the Planck era, the Universe can be best described as a quantum foam of 10 dimensions containing Planck length sized black holes continuously being created and annihilated with no cause or effect. In other words, try not to think about this era in normal terms. The first moments after the Planck era are dominated by conditions were spacetime itself is twisted and distorted by the pressures of the extremely small and dense Universe. Most of these black holes and wormholes are leftover from the Planck era, remnants of the event horizon that protected the cosmic singularity. These conditions are hostile to any organization or structure not protected by an event horizon.