Table Egging

So purchased a large egg and I'm building by table, installing my granite top next week.  I haven't put the egg together yet so maybe it would be best to install the granite top, then the bottom half of the egg for weight concerns, and build the rest of the egg in the table?

Also, I've seen many topics on this but am just looking for confirmation.  I have a 21" hole in my granite top and am using a table nest.  The granite that the nest will be sitting on will be just about flush with the shelf.  I'm thinking the height should be 16.5" from shelf to granite top?

Thanks!