next friday you'll be 8 months, but *in* your 9th (as in you'll just be starting your 9th month).
2 weeks after that you'll be 8 1/2 months.
your due date marks 9 complete months.
edit: this is what i do...
i'm due april 6th, so i go backwards from there. so on november 6th i'll be 4 months, around nov 21st i'll be 4 1/2 months, dec 6th will be 5 months, etc. if someone asked me today i would say "i'm almost 4 months".
my method and rachel's chart are the same thing.