I made some changes. I added year 1926 and removed 17J. I have never seen a 17 jewel 6P and the file Will refers to above is just a 15 jewel 6P, not 17 jewel.
But......there are 2 6Ps. The first one is a 16 jewel one from 1924. It looks exacly the same as its predecessor, the 6PP. The 6P with 16 jewels have serial numbers from 40 thousand to 60 thousand. Then as from 60 thousand, other 16's take over from the 6P, being the 6E, 6N, 6R and 6W until serial numbers around 100 thousand. Then is it over for the 16's and the second 6P is introduced in 1925. It looks exactly the same as the future 6AP. It runs from serial numbers 106 thousand to 128 thousand, the latter stamped as 1926 before it is taken over by the 6AP in 1926 starting with serial around 130 thousand.
6P noted as 17 jewels w/ Asterisk date code evidenced in pics in this record. http://www.mybulova.com/node/5202?page=1 1925 Bulova model 6724.
Two 6P in movement database. One 1925 w/ 15J -details added to this record 2012/24/23
I have one with no date code
Star date code, earliest date code according to chart in database.