Can't find the answer any where REp if you can help

i live in NY near Niagara Falls, I normally grow indoors and this question would be simple to answer. I use the fox farm line and the open sesame is used a week before flowering to open the pours then used for the next three weeks then beastie buds and so on... So sept.26th is the day that it goes to 12 and 12 outdoors but i know from past experiences that plants are usually done around the harvest moon which is October 16 first frost starts soon after. Now do i start the open sesame back 67 days from that date (plants are 60 day flowering) or what that would be in five days and the hours of light a day are 14 of light and 10 dark. Does that seem right PLEASE HELP ME!!!!!!

dont stress dude, just start using it when you start to see them go into flower. You got to remember that in the US most plants tend to start flowering late july to late august, way before the light cycle actually hits 12/12. and just continue to use your cha ching in the end until you see the buds ready, you can't always count on the "60 day flower" period. They will be done when the tichomes tell you. Good luck