I actually think it's the +(16)and [1][1][2] top of the FBI [19] that need to be cleaned out, with McCabe being the 2 that already toppled and the [3] at the top of State. DOJ is being handled with the top 3 there out of office already or neutralized. The +41 in State and other 21 in FBI can be taken at any time.
The waiting is removing any last failsafes and sleepers they have out there. The sub was the big one. Marines out there doing work. Once it's safe, IG releases. The constant flurry of differing dates is to keep everyone off balance giving some thinking they have time and others paranoid it's coming tomorrow.