A rather simple answer to your question will be answered by this one comprehensive article that we wrote on history of Vioxx and its recall. We did another article on Cox-2 inhibitors and that too takes a look at the sequence of events with regards to Vioxx.
I don't think anyone knows when people started to die since that information has not been documented yet, but I am sure that lawyers will do that as more cases get filed. The FDA has done a statistical analysis of number of deaths but that report does not include who died and when.
Some recent reports indicate that Merck may have known as early as 2000 that Vioxx was dangerous.
Recommended link: Vioxx litigation update