It depends where you get on. The bus route starts at the POR south depot, then West, East, then PRFQ before going to DS. I would plan on at least 1/2 hour after you get on the bus.
The route starts at FQ and then goes to RS for all 4 stops and then back to FQ. It’s considered an internal shuttle. It’s a long run and depending on where you get on and the time of day I’d give yourself 20 to 30 minutes.