Of all the awful news from back then, the item that most struck home to me was the failure of Washington Mutual, which Wikipedia says happened on September 25, 2008. I would have guessed it happened a little earlier, but most likely that's because rumors of its imminent failure were already circling.
There were two reasons this news made an impression on me. It was the first time in my life that a financial institution failed in which I personally had an account. I had a credit card with them, which at the time was maxed out in a 0% loan.
That by itself would have been good reason for me to sit up and take notice, but even more striking was the peculiar incentive WaMu gave me to take the 0% loan in the first place. As I recall, they gave me the entire 1% credit card cash back on the loan. So here we have an example, absolutely unique in my experience, of a financial institution paying ME to borrow money from THEM. Even with my limited knowledge of how banks make money, this struck me as a rather counter-productive way for WaMu to turn a profit.
So my personal awareness of the huge magnitude of the crisis didn't happen until right around the time it became obvious to everybody else as well. I think this is a fairly inevitable byproduct of me being a buy-and-hold, ignore the financial noise type of investor. On rare occasions "noise" escalates to "news that you really should pay attention to". 2008 was one of those times.
If I had correctly identified the scope of the crisis in a more timely fashion, I would have done only minor things differently. Mostly I would have held off doing any rebalancing in the summer of 2008 and waited until the height of the crisis in October. In perfect 20/20 hindsight, I should have sold all my stocks in late 2007, but there is no chance at all I would have done that. I was in the process of building up my stock holdings from a floor of 15% and would have looked forward to the crash as a great buying opportunity.