They should go back to 2007. Even better would be 2004, when corporate and union donations were limited to $1,000 annually. That was effectively a ban. The audit should look at that whole period. Elections Quebec waited from the late 1970s until 2011 to finally do an audit, and what did they find? Funnelling. Why would Elections Canada wait 30 years, as Elections Quebec did?
On October 5th, 2017. See this statement in context.