I meet lots of cool people (men and women) at Meetups but attendance tends to be Inconsistent. So I don’t know when or if I’ll see them again.

When should I grab the number? On one hand, I don’t want to be the creep who scares her away and prevents her from coming back (and getting kicked out of the group) but I don’t want to pass up a chance with a friendly woman, especially if I don’t know when or if I’ll see her again.