Likely you are. Don't ever count on anything in particular occuring unless you have grown the strain before and are somewhat familiar with it's peculiar growth cycle.
Not trying to be vague or condescending, simply offering some thoughts.
I have had abysmal luck in trying to grow and harvest any strain in a manner that resembles what the company states it should roughly be. When I see "8 week strain", I interpret that to mean 9-11 weeks.
Im not implying that they are being dishonest, I do n ot think that they are trying deceive anyone. In my case I've concluded that my grow is simply not as fine tuned as a commercial outfit likely is. That is why I assume it takes me longer.
Keep on growing your plant (s) how you think is best, and I'll be you end up just fine.