Not the earliest (before Feb 1928) which was a tray held to the oil pan by four bolts.
After February the pattern changed to the "snap in groove" - which this one appears to be -but it took a while for the dipper grooves to widen. Also, the snap in started "small" and was later deepened. This one appears to be this "interim" pan which I would put "After February 1928" but before the change to "most modern."
I just checked my July 1928 AA truck and it has snap-in grooves. Also the bolted cover below the oil pump which was eliminated "early 1929".
Joe K