Also the early BOL dial photos mentioned all show the keyhole style control escutcheons for the six control shafts, and scratch suppressor button below the dial. So appears the 1939 Philly was the same chassis as the 1937-8 pointer dial model, just with the new Strad BOL dial.

The intro of late 1939 for the new 1940 model appears to be  when other changes also took place as well: separation of the treble control from the fidelity control, reposition of the scratch suppressor to complete for the 8 control look, the round control escutcheons, putting the power switch on the volume control, and some circuitry changes  as reflected in the parts changes listed in Riders info. 

Scott has a reputation of evolution of a model, so maybe there are later 1939 models that incorporate some but not all the changes announced for the 1940 model Philharmonic.

Some of the changes for both the Philharmonic and Phantom Scotts for 1940 may also have been preparation for the FM  models being developed and soon to be announced Spring 1940.

the logging scale in the form of the little window at the top of the Philly and Phantom Deluxe was introduced late 1939 as new for 1940 model, available late 1939.

Previously, the logging scale micrometer dial was part of the Fall 1936 enhancements to the AW-23 which also included the new Super Shield Antenna Coupler and 2nd antenna post. This micrometer dial was available to update earlier AW-23 and AW-15 dials, which required some alteration to the back side of the wood panel. The Pointer Philly of 1937-38 had a logging scale as did the model Sixteen ... and the early production single chassis Super 12 before the introduction of the Stradivarius dial. The logging scale was subsequently omitted for the Philharmonic BOL Stradivarius dial introduced late 1938 and  that still had the control configuration of the Pointer dial model.

But, my Philharmonic has features of the 1937 one, and the logging scale, so the dial is a later addition.