Never can tell. You can also go activate them at Disney Springs at one of the 2 guest relations spots. That's where we went a few times and it was pretty quick. You really never know from day to day how busy any location will be.
I have never waited more than 10 minutes in this line. We usually arrive about 30 minutes before rope drop when we have business there, and one or two people in front of us. We have been there at almost all times of the year.