Even with fast internet it seems the Manga Rock servers are limiting me some. I used Free Manga Downloader to download everything (from a dozen different sites at once) I was going slow (about 4-6GB per day) but with Manga Rock closing I deiced to focus on it only at full speed of 80-85 GB a day.
I then ordered the downloads from smallest chapter count to largest, downloading the smallest first. Larger series can be found else where in the worst case if I don't finish downloading. I do not have an exact date on the close. They are still adding chapters. The closest is Second week of September. Which could be the 13th to 15th
At the moment I have downloaded everything with 1 to 48 chapters in it. Currently have about 1600 out 16610 left.