User blog comment:Maria Trimble/Death in Supernatural Shows/@comment-67.142.182.21-20130619225531/@comment-4091815-20130622031339

Yeah - that full moon in March was a deadline - he had to do it BY then.

Think about how long it took Lydia to really start hallucinating him - getting her up to full throttle took some time.

Also - there were only two full moons in Season 2 the one during Shape Shifted and the one during Party Guessed. So only one would have passed before his resurrection