As far as I know, when the sundial is spinning, it doesn't do anything, it just happens between 20:00 (8:00 PM) and 21:00 (9:00 PM).
To know if your Mega Ring is upgraded, look in your bag, if you have any of the Mega Stones listed under "Post Game" here (Excluding the Mewtwoite X, Mewtwoite Y, Gardevoirite, and Absolite.) your Mega Ring is upgraded, if you don't, it still might be upgraded.
If you don't have any of the Mega Stones listed under "Post Game," try going to Laverre City. Between the times 20:00 (8:00 PM) and 21:00 (9:00 PM), there will be a sparkle in front of the well if your Mega Ring is upgraded, the sparkle will not be there if it isn't upgraded.
Hope this helps!