The 1946 Mark 1 (ASCC) manual by Howard Aiken, Grace Murray Hopper, et al, has to be the first one which:

* Is a technical manual, for a digital machine, which was actually manufactured (only one ever was made, but that's more than the zero actually made of whatever the Lovelace/Menabrea paper(s))

* Contains instructions for programmers, starting at page 98.

* Pages before that have a lot of design information in the preface, and hardware data.


[PDF is online here.][1]


 [1]: http://chimera.roma1.infn.it/SP/COMMON/MarkI_operMan_1946.pdf