I thought this might help some of us in the waiting lines. I went through all of the posts in this Scarborough forum and calculated the following table in Excel. Time Frame used here is for all the applications sent since August First, 2014. By "Step" I meant the length of time required from one step to the next. # Samples means the number of dates mentioned in the posts.
I canceled an overseas trip of mine in May because the table average indicated a test date is coming up during the trip (and it did). I hope this gives a better idea of waiting periods for the anxious ones among us.
Step #Samples Avg. Days Min Days Max Days
App Sent -> Scarborough .. 18 117 74 206
Invite Letter -> Test ......... 9 14 10 20
App Sent -> Test ............. 29 177 127 232
Scarborough -> Test ........ 14 55 33 88
AOR to Oath .................. 8 161 70 235
Scarborough to Oath ....... 2 125 113 137
Test to Oath .................. 13 36 20 76
Good luck to all.