Please tell me, how much time does it take to convert a regular VHD disk to a managed disk ? It all depends on the size and type of OS. I couldn't find this information. Thanks.
There aren't any published SLAs for conversion and the time taken will vary depending on VHD size, time of day, region in which you are storing the managed disk etc.
As a very rough estimate, a 240GiB VHD stored as a Blob should take in the region of 1 minute. So we're talking in seconds and minutes rather than hours.