Perhaps I am not familiar with their exact policy. I was just thinking that something he said to SI could be construed as hearsay and not proof. Kind of a grey area. Did he say when he did it? What's the policy on punishing someone for simply saying that in the past they tried something that contained an illegal substance? Even though it's not exactly the same, could they really do anything if he stated in an interview that he smoked a doob when he was out one night when he was 25. Sure it happened, but he wouldn't test positive for it now and how do you prove that he's not just telling stories. Don't know why he would, but still...
Hearsay is when someone else says they overheard you saying something. Since it was said in an interview, yeah, you can claim you didn't say it. Problem is, Vijay admitted after the article came out that the article was accurate (so much for the "that's not what I said" defense).
Here's Vijay's public statement of admission that he used the product:
Here's what Vijay said he used according to the SI article: http://www.shop.swatsedge1.com/SWATS-The-Ultimate-Spray-002.htm
The ad clearly states that it contains IGF-1, which is also on the banned substance list.
Vijay has since submitted a sample of the spray to Tim Finchem for analysis to see if it does actually contain IGF-1. (this is where you hope that the company lied about it's ingredients)
Here's a link to the FAQ for the PGA Tour Anti-Doping Program.
The following is an excerpt from the FAQ with the relevant stuff in bold:
What other conduct violates the Program?
Other conduct may lead to the finding of a violation and sanctions under the Program, including the possession, use or attempted use of a prohibited substance or method; refusing or failing to be tested; tampering with a sample; trafficking in or administering any prohibited substance; or admitting to any conduct that violates the Program.
You may not be able to find the entire 2013 manual online, but here's a link to the 2009 PGA Tour Anti-Doping Program Manual.
It has details about punishments and procedures as well as the list of banned substances as of 2009.
As far as I can tell, his only hope is that the spray doesn't have any IGF-1 in it.
Again, it doesn't matter if he's telling the truth or lying when he said he used a banned substance. Simply admitting to using a banned substance is enough.
Oh, and to answer your question of "when", he said he bought it in Nov 2012.