First, a little primer on conservation of energy and the uncertainty principle as described by Et<=hbar. This means uncertainty in energy times uncertainty in time is less than or equal to plank's constant. It allows for the violation of the conservation of energy for a brief period of time. We see this proven experimentally in multi-photon transitions.

Consider a genuine timeless void, no matter-energy, entropy or time. If we introduce an arbitrarily small age to this void, it can contain an arbitrary amount of energy. If this arbitrary energy is not appropriate for a big bang, no universe will be created, and the arbitrary bit of time becomes essentially virtual - it does not happen. If the energy is appropriate for a big bang, a universe is created, and time becomes real and continues.

So, essentially, an unlimited number of virtual instants could pass without creating a universe, but an instant that could make a universe was unavoidable.

Njorl