It was the lack of such a lead time that caught CDS issuers, like American International Group (AIG), with no time to adjust their risk portfolios, and required government intervention to prevent a domino default effect. With Greece, no such domino effect is expected although there is always the possibility (albeit low) of a surprise. We will know that soon after the March 19 auction when settlement must occur.
This is not to say that the world is now safe from financial contagion, as, in the context of world markets, Greece's default is an expected and well prepared for event. The real worry should be if Spain, with a debt of about $1 trillion and/or Italy with a debt of about $2 trillion default.
In addition, the CDS market is not transparent, and no one knows where the CDS obligations lie. While a Portuguese and/or Irish default would have about the same individual impact as that of Greece (economies slightly smaller and not as indebted), we should worry that a rolling set of smaller defaults would eventually cause a major CDS insurer to fail due to the cumulative impact of the several defaults.
After all, it is likely that the CDS insurers who dabbled in Greek CDS, are also involved in CDS insurance of the other high debt European countries. And, if a significant CDS insurer defaults (e.g., an institution similar in size and stature to AIG in 2009), we could, indeed, have contagion.