The timer starts when DCSA “schedules” (accepts) the SCA. This is after the back and forth to get Subjects to just fill in the blanks. The time stops when adjudicated.
Keep in mind that if we process a million cases a year - the fastest 90% are 900,000 cases and 100,000 can be the outliers.
The other elephant in the room is that DCSA processes approximately 95% of all background investigations (old data, I don’t know the current workload) while 8 other ISPs (investigation service providers) do the remaining 5%. And … that 5% includes all DOS and most IC clearances. The agencies that are not measured by their timeliness and whom seem to be the majority of the long term Subjects in this forum.
I have often seen the SD in the week previously where I complete the case (T2/3/4/5) the next week, and seen the case is closed by review the following week. There is luck. There is investigator experience. There is also, most importantly, Subject and Source cooperation.
One to two week cases can be done, even if everystar and traffic light does not line up properly.