Assuming the recently announced deep space travel project [1] works out and their estimates are correct (unlikely), it would take 20 years of preparation + 20 years of travel + 4 years of data transfer.
Also mentioned in [1] is that if Voyager 1 was headed for Alpha Centauri it would take 70,000 years.
Related question: If some other advanced civilization sent us one of these iPhone sized computers, do we have the technology to detect it before it zooms past our planet or burns up in our atmosphere?
Also mentioned in [1] is that if Voyager 1 was headed for Alpha Centauri it would take 70,000 years.
[1] http://www.nytimes.com/2016/04/13/science/alpha-centauri-bre...