I found this partial study to be very interesting. Unfortunately, it is just the first page and I can't find the whole study. But according to it, you might want to gather your pollen in the morning, and then wait 12 hours before you pollinate your female plants. EFFECT OF THE AGE OF POLLEN UPON THE SEX OF HEMP. (USA) (1st page – 1928) Error - Cookies Turned Off Granny
You're right, that's very interesting and I'd love to see the whole thing but perhaps it's not the age of the pollen at all, perhaps the time of day pollen is applied is what affects the sex of the seeds. Maybe sleeping plants (plants in the night time cycle) accept female pollen more readily than male or the effect of light on the plant gives a higher likelihood of the seeds being male. If it was the age of the pollen then further experiments using pollen collected the previous day or so should show more female seeds than male.
similar study but of wind direction..? by Small and Antle A Preliminary Study of Pollen Dispersal in Cannabis sativa in Relation to Wind Direction Journal of Industrial Hemp, Vol. 8(2) 2003 Home | Taylor & Francis Group 10.1300/J237v08n02_03