Last week, Google quietly announced on Google+ a new feature to help advertisers understand the time it takes for their customers to convert after they click on their ads. Google wrote "we're introducing "Days to conversion" reporting to help you see the time between ad clicks and conversions."
So this report lets you get a quick snapshot on how long it takes for your customers to convert. Google wrote:
You can apply the “Days to conversion” segment to your AdWords report to see the number of days it takes people to convert after clicking your ad, for all clicks during the selected date range. For example, you might see that 90% of purchases for your washing machine campaigns usually happen 14 days after a click. With that insight in mind, you may want to wait 14 days to get a more complete picture of performance before adjusting bids.You can also use this data to help inform your promotion calendar. For example, let’s say you notice that most of your customers click on your beachwear ads in May, but don’t convert until your summer sale in June. You can use this information to adjust the start date and duration of future summer promotions to maximize sales.
Here is a GIF of the report in action:
Forum discussion at Google+.