Installing posts for the roof garden railing

City of Boston building code requires that the red brick building's roof garden be fenced in and dictates the height that the fence needs to be and the distance it needs to be set back from the edge of the roof.  We are having wrought iron railing made that's a simplified version of the balconies' design.  It's supposed to look like this:

This week, our contractor has been installing the bottoms of the posts for the railing.  The top part of the posts is a slightly smaller diameter, so when we're ready for it, it will slips inside the "sleeve" that's now being installed.   Here's the progress, as of quitting time yesterday:

After all of the posts have been anchored beneath the deck of the roof, our roofers need to come back and seal the holes around the base of each post.  Then the roof will be ready for our greenroof subcontractor to begin installing the protection and drainage layers, the drip irrigation system and the soil.  We are hoping they'll be able to do the work the last week of April, since they have another job booked the first part of May, but as I've learned with this project, as soon as you start counting on something happening by a specific date, you're setting yourself up for disappointment, so I'm not holding my breath.