Snapmirror Initialize transfer time/data

We about a 3TB snapmirror destination that had to be rebuilt from scratch at our DR and I'm trying to figure out how long it it suppose to take.  I was using the Snapmirror Progress Tool, but the time was not reporting correctly due to size.  Also the amount that it stated we had left has lapsed.  (It also stopped working all together, but that's a different thread.) 

What I'm trying to figure out is what is the best way to find out how much data is left.  I was thinking that if I take the size between the delta of the first snapshot on the volume and then the most recent busy snapshot and then add them to the size of the data space, that it would give me a rough estimate of how much space is going to be copied during the initialization.  (I know it will have to do more snapmirror since it has some delta's that haven't been touched yet.).  I just want to figure out how much space is left in the initialization.

Not sure if it matters but we are running 8.0.1P4 on all of the heads which are FAS3210's.

Thank you.

Snapmirror Initialize transfer time/data

Do you mean something like running a "snapmirror status" on the cli? The snapmirror log allows contains some progress data.