TheOptimizationIdiot - 2:58 pm on Apr 19, 2013 (gmt 0)
Depends on a number of things, including your crawl frequency.
One thing I've noticed is lately they've been snail slow in updating to new locations. I've had cases where a page has been redirected for 3 weeks, the title is from the new location, the information on the page in the preview is from the new location, the breadcrumbs in the results under the title are from the new location but when you hover over the title or click the old location is linked.
There's no way they have all the new info from the new location of the page, are displaying it in the results for the page, but haven't found the redirect yet, so there seems to be a delay in updating the old URL to the new URL in the system at times. It hasn't happened every time, but I have seen a definite lag between them finding a 301 and updating to the new URL recently.