Barring an exceptionally crowded day, wait times for the Safari usually are around 5 to 25 minutes in the hour after opening. Last time I was there, I rode about 45 minutes after opening with a 15 minute posted standby time and was on the truck in less than 5 minutes. Personally, I wouldn't bother showing up too early before opening as it'll just be extra time standing around if you're going straight to the Safari. If you do show up early, keep in mind that: (1) AK typically lets guests into the park anywhere from 15-45 minutes before the official opening time (mostly the FoP crowd); and (2) Pandora is the only area of the park that will be open and running early. This means that if you do show up ahead of time and get into the park, you'll just stand over at the bridge to Africa until they drop the rope around official opening time and you can walk back into Harambe. I did that last year and had around 75 other people doing the same - not much more than the first Safari truck out of the station would hold.