I think you mistook the last 20 additional miles for the original authorizations.
The $2.5 billion from Department of Defense 10 U.S.C. § 284 Counter-Narcotics accounts was used for three rounds of project approvals.
1. First, $1 billion ($976 million) was transferred in April (https://www.thedailybeast.com/army-authorizes-use-of-dollar976m-of-counter-narcotics-funds-for-border-wall) to fund two projects - the 46 miles in New Mexico (which has been awarded. and is currently under construction), and an 11 mile Project in Yuma Sector (also now under construction).
2. Then, $1.5 billion was transferred in May (https://www.defensenews.com/smr/federal-budget/2019/05/13/us-air-force-nuclear-space-programs-take-hit-in-border-wall-reprogramming/) to fund two more projects - 63 miles in Arizona (Lukeville, Organ Pipe, Cabeza Prieta) and 15 miles in the El Centro Sector of California (Jacumba Wilderness). Both of those projects have also been awarded and are currently under construction
3. Finally, in August, DoD anoounced (and later cancelled) the 20 Miles (3 Projects) that you refer to. When the SecDef authorized the original four projects in April and May, they made sure that there would be enough money set aside to pay for the contracts. The final accepted bids were less than the conservatively high amounts that had been reserved, and additional money was left over. They tried to scramble in August to get more barrier built with it, by hurriedly designating three more small projects.
I believe that the cancellation was probably because they were just unable to get the money awarded on contract and obligated before the end of the fiscal year. That type of money (Operations and Maintenance, Army, or OMA) is one year money, which expires on 30 September if not obligated. They probably just re-programmed the money back toward other pressing DoD requirements, that were ready to obligate quickly. That kind of thing happens a lot as the end of the fiscal year nears.
One of those three Projects cancelled (North of the Morelos Dam in Yuma and around the Andrade Port of Entry) has been included among the 11 being funded with Military Construction (MILCON) money.
A total of 135 miles is funded, and currently being built, with DoD Counter-Narcotics funds. The use of these funds on those projects, was the subject of the Supreme Court's decision in July (case No. 19A60 Trump v. Sierra Club).
"How many miles of drug money fence completed? Zero."
Currently, at least four crews have been working concurrently on those projects, so I would conservatively estimate that at least two miles have been completed among them. Just one of the the three segments of the Arizona Project is scheduled to complete two miles by 1 October (around the Lukeville Port of Entry).
Next month, additional crews begin work on the other two segments of the Arizona Project, and another segment of the Yuma Project. I don't know how many crews are working on the New Mexico Project, but I anticipate that at least a second crew will be needed to work concurrently, for them to meet their delivery date of October 2020.
So just the Counter-Narcotics money ($2.5 billion) will be building a solid 2-3 miles of wall per week, by next month. Separately, both the bulk of the 2018 and all of the 2019 appropriations (~$2.8 billion) and the MILCON money ($3.6 billion) are just starting construction, with a bunch of new contract awards and groundbreakings over the next several months.
The construction activity that we had seen up until January of this year (2019), was just the effect of the $400 million in 2017 appropriations (40 miles). In January of 2020, over twenty times as much money will be working. This is full scale deployment.
This is also your wake up call, that it is no longer going to be reasonable to say that President Trump is doing nothing on the Border Wall. There is a tsunami of construction beginning, and we will have to update our assumptions to the new realities. It took a huge amount of effort and determined Presidential emphasis to get us to this point. In truth, it was never the case that President Trump was not really committed to building the border Wall - the results were just not as visible as they are now. By next year, it will be be dramatically obvious to all.
DoD Counter-Narcotics money now at work on the Border Wall:
Start of the Lukeville Segment of the Arizona Project (27 Aug) - the first panel of of 63 miles:
Start of the Yuma Project (5 Sep) - first 5 mile segment of 11 total miles:
Start of the New Mexico Project (23 Aug) - extending President Trump's earlier (FY17 funded) 20 mile segment, 46 miles further (MILCON money will add a further 13 miles more to this run):
Start of the El Centro CA Project (22 Aug):
The Commanding General of the US Army Corps of Engineers, LTG Todd Semonite, observers the first bollard panel raised for this 15 mile segment.