It doesn't seem that he had any clue about the flowering time. Seeds were wasted on him.Hi Marc,
I'm a sativa lover too but have never had the nerve to do what you're doing. Patience will be your best tool.
Where did you get the seeds?
Pure sativas like that will be light feeders and they like intense light from a single overhead source. (from DJ Short's book)
Carry on,
JD