For me it wouldn't be a question of 'if I buy today, how long until it comes good'. It would be more a question of .... I like the company, is it cheap now; is recovery in the long term probable? Meanwhile the stock has to be a fully self-sustaining proposition .... or it's a punt, a gamble.
I don't do gambles. As, the VW saga is now totally known to the market, so there is no 'unknown advantage'. Just the bad odour left behind.
What are the VW metrics like now? Earnings, divs? Does it stand on it's own feet? I haven't looked but given the context I'd be looking for say a 7+% div. Have they cut the div yet, will they? This is the sort of thing I'd be looking for next.
There are usually less stressy ways to do things like this, hitting blue-chips where the sector is slightly out of favour and waiting for the sector-cycle to rotate *whilst reaping solid divs*. VW would be a very long term recovery play (I suspect) but why give years to that chance (when others won't), and meanwhile many opportunities are there in the background, most of which are far less long-term and toxic than VW is right now....
RDSA (ie Shell, $ listing) 7.98% [analysts rate 'Overweight']
Billiton 7.97%, ditto
BP 7.81% ditto [lots of oil/resources in these three.... but consider loooong term]
HSBC 6.54% ditto
Even Vodafone is on 5.16% [ditto overweight ranking from analysts]
p.s. I've held 4/5 of above, all but BP, as RDSB was the better oil stock for me at the time.