I really don’t know, some people will be giving more than $100 on that day, others signed up but will forget or give less, others will be giving, but haven’t signed up.
I don’t know which of these groups will be higher than the others, your estimate sounds as good as any that I’ve heard. Anywhere from $1.5-3 million is most likely, IMO.
I can tell you 45 people from the LV meetupgroup have signed up for it on our site, but I don’t know how many of them are also subscribers to the nov5th site.