Fantasmic, how early to get in standby line

How early should we get in the standby line for Fantasmic? We are not worried about getting good seats we would actually prefer getting seats in the back for an easy exit. We will be there March 2nd. Crowd level is predicted to be a 3. One showing of Fantasmic at 7:00. Park closes at 8:00.
Thanks,

DH and I showed up about 20 minutes before showtime on a similar sort of day a few weeks ago, though the one show was at park close. Standby line had already been let in so we just had to walk the length of the queue and sit down. We ended up maybe 3/4 of the way back in the second to last section on the side.

I agree; 15-20 minutes should be fine especially with that crowd level. Lots of good seats.