^
I drove the length of the project last Saturday morning - I agree that the project doesn't look on track to finish by December east of exit 52 (with the main holdups appearing to be flyover construction at the more complicated interchanges), but west of exit 52 does look on track. A lane shift within the exit 52 interchange puts westbound traffic on the 2 eventual-HOT lanes & 2 of the eventual-GP lanes, with the rightmost GP lane currently coned off.
Not the greatest quality, but here's 4 photos I took:

Westbound at exit 62 & the Vienna Metro station, with the 4 lanes temporarily divided into 2-&-2 thru the interchange area

Westbound approaching exit 57, with traffic shunted all the way to the right

Westbound at exit 53B, which now departs the mainline well ahead of the actual interchange so that HOT-lane traffic can cross the flyover in the distance and merge with this ramp prior to reaching VA 28

Westbound approaching the Manassas rest area (easy to forget it still exists) - after the aforementioned lane shift at exit 52, it took me a while to realize that the solid line between the middle lanes was because I was riding on what will eventually be the right HOT-lane!