They stopped allowing guests to line up pre-park opening at the start of last summer. They've also stop distributing FPs when RSR is down. So if RSR is not open when the park opens, they do not distribute FPs either. Combining those things, along with connecting RSR to the DCA FP system, really seems to have affected RSR FP distribution duration. I remember when the FPs used to run out in the first 30 minutes too (you basically had to get in line pre-park opening or you would miss out), but those days seem to be over. I still wouldn't wait to long into the day, but I think on most days you'll be safe as long as you get there within the first 90 to 120 minutes of park opening.