The reminder email says:
We noticed you have not accepted our invitation to join Stack Overflow Careers. Only 3 days remain before it expires [...]
But please act soon: this invitation expires in 14 days [...]
Is it 3 days or 14 days now?
Here is the full text of the email:
We noticed you have not accepted our invitation to join Stack Overflow Careers. Only 3 days remain before it expires, and we’d love to have you. In case you missed the invitation, or never got it, here it is again:
In recognition of your contributions to Stack Overflow, we’d like to invite you to create a professional profile on Stack Overflow Careers.
A Stack Overflow Careers profile is a great place to showcase your professional work as a programmer – Stack Exchange answers, open source projects, even the books you’ve read.
Click here to accept the invitation. It’s free!
Even if you’re not looking for a new career today, your Stack Overflow Careers profile will be your professional home on the web. It lets your colleagues, friends, and peers know who you are and what great work you’re doing. It’s a terrific way to build your professional reputation and take your career to the next level. And it’s fun!
You’ll always have complete control over what’s in your profile, who can see it, and whether or not employers can contact you.
But please act soon: this invitation expires in 14 days, so sign up now!
Even if you decide not to join Stack Overflow Careers, we would like to thank you for all your contributions to Stack Overflow. It wouldn’t be the same without you.
The Stack Overflow Careers team
The "14 days" bit is in the quoted text from the original invitation.
So you had 14 days when you first got the invite, and now you've only got 3 days left.