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Adam has pretty much hit the nail on the head. We can see back to ~ 380,000 years after the Big Bang, before that time every atom in the universe lived in a plasma which was virtually homogenous and isotropic except for some very minor fluctuations which are visible in the CMB as the warmer and cooler patches.
There is no real evidence for anything before the CMB. We know the universe had a beginning and if we use the cosmological constant as reverse back from the size of the universe as far back as we can see we know roughly when it began... As long as the universal constant was actually constant during that period. Much of this hinges on whether we are an open, closed or flat universe. Currently we are considered as "flat" meaning that the cosmological constant is actually constant. In an "open" universe the Hubble Constant was slower in the past and continues to increase in speed over time. In a "closed" universe you could say that it'll eventually reverse direction and we'll have the Big Crunch! That's probably the most exciting of the theories as it means that the universe restarts every few trillion years.
The universe starting as a dot in the most logical if you think of the universe as "flat" as it started somewhere at some point and expanded from there. Much like what happens behind the event horizon of a black hole, we don't actually know what happens when we compress matter excessively. A black hole to us is really just the event horizon, a point where the gravitational well of space time is steeper than the speed of light. As for what happens in the cosmic soup before the universe became visible? Lets peer into a black hole and see :wink:
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