Spermatogenesis in humans - timing of phases and chromatin modifications
Spermatogenesis (Beginning to end):

64 +- 8 days (range 42 to 76)


There is considerable individual variation. This includes time in epididymis.

Amann 2008 argue for 74 days based on early study by Clermont 1972.
Also argue that biopsies are still needed on top of radiolabelling. 

Substages:

Calculated from Amann 2008, Figure 1 using percent time in 16 day cycles.

Leptotene: 

26.5 days (~70 days total - 26.5 days = ~ 43.5 days pre-ejaculation/conception)


Zygotene: 

31.2 days (~70 days total - 31.2 days = ~ 38.8 days pre-ejaculation/conception)


Pachytene: 

32 days (~70 days total - 32.0 days = ~ 38 days pre-ejaculation/conception)


Histone-Protamine transfer:

68.8 days (~70 days total - 68.8 = ~2 days pre-ejaculation). 


The resolution of the data doesn’t really let us get at Epididymis vs. histone-protamine transfer, though.

Time in the Epidymis:

10-14 days. 


References:


  Misell LM, Holochwost D, Boban D, Santi N, Shefi S, Hellerstein MK,
  Turek PJ. 2006. A Stable Isotope-Mass Spectrometric Method for
  Measuring Human Spermatogenesis Kinetics In Vivo. The Journal of
  Urology 175:242–246.
  
  Amann RP. 2008. The Cycle of the Seminiferous Epithelium in Humans: A
  Need to Revisit? Journal of Andrology 29:469–487.
  
  Durairajanayagam D, Rengan AK, Sharma RK, Agarwal A. 2015. Sperm
  Biology from Production to Ejaculation. In: Schattman GL, Esteves SC,
  Agarwal A, editors. Unexplained Infertility. New York, NY: Springer
  New York. p. 29–42. Available from:
  http://link.springer.com/10.1007/978-1-4939-2140-9_5