Availability of W8.1 for 520

Just download the developer preview, its simple and even my mum managed to do it on her own. If your talking the official release I believe summer was the said time but that being dependent on your carrier now that maybe very quick or may take months!
 
One of my friends got it through the Developer Preview program. So yes it's available for Lumia 520. If you want it now use the Developer Preview program or if you can wait for the official release then wait for some time. But you'll obviously get it on Lumia 520 and that's for sure. :)
 
Wp cant ever b better than android.....android regularly updates os n apps. But wp....wait wait wait......cant say months or a yr....