I suspect that it was around then that he got hold of the "bonds". In spring-summer 2007, he hired Zuzanne Kanaty, supposedly to help broker the Meta deal. But of course there was no Meta deal. So what was Zuzanne really doing?
We know that Sid had the bonds by January 2008. My guess is that he acquired them the previous summer.
In February 2008 he first presented them to HSBC, and was told that they were forgeries...