assuming it's legit headband, then its the OG cut reversed and used to pollinate the sour diesel.
contrary to popular belief, OG Kush, is not a kush (at least genetically). it's a chem/dawg descendant which is a hybrid that leans more towards the sativa side of things. the sour diesel used (not to be confused with soma's NYSD or soma's NYCD) is also a descendant of the chem/dawg genetics.
since both of the parents are sativa heavy hybrids, i'd expect a 10-15 week flowering time, but pick up a 30x-100x pocket microscope from radioshack for like 19.00 and you wont regret it
harvest time is relative to yer taste, I like to let 'em go for a while for pain relief of a later harvest, while others harvest earlier for a good "head stone". The great thing about this harvesting thing is one may take a few buds every few days if ya want to so you can taste the different chemical changes they go through at this stage of growth:>)