I would think you have to be 18. It's being given by her friend (also 17), so presumably is in the mother's name. DD says the mother will be there. To me there's something a bit creepy about having an AS party with your ma, but anyway... I know she's had sex, and I want her to know about sex toys at some stage, but just not yet!
The last AS party I went to, the demonstrator had brought a trainee with her, who was 18. My friend turned to me & said it was a shame, a sort of loss of innocence, and I feel this about my DD. I also don't respect this particular mother - her DD has just got her 3rd tattoo (underage, don't forget) and the mother went with her to get it, so was done in full knowledge. AIBU to think that it's all too much too soon?