OG late boot stage

I am reading that it is best to harvest OG during the late boot stage.... or early boot stage???  I am having a hard time figuring out when this usually is in Michigan in the spring time.  I'd like to get first cutting next year started at the proper time so all subsequent cuttings are more lined up.  I understand weather plays a large factor into this but just looking for some insight.  I'd like to cut every 6 weeks after first cutting "weather permitting."

 

For highest quality hay, orchardgrass should be harvested in spring during late boot to early flowering stage. Beyond this stage, digestibility decreases at the rate of about ¹/₂% per day. Aftermath growth can be harvested at 4- to 6-week intervals. Production and cutting frequency are greatly affected by soil moisture, temperature, fertility, and disease.

 

and I read this....

 

Cutting and grazing management greatly influences forage quality, productivity, and persistence. Quality is most affected by maturity stage at harvest. To obtain high-quality preserved forage (hay or silage), harvest orchardgrass at early boot stage. See Figure 8. Delaying harvest until head emergence or early bloom increases yield but reduces quality and regrowth.

OG late boot stage