It takes about a year, It can get thick and full in about 2-3 months but it wouldn't be as long as the ones in the pictures. Beard hair takes its time to grow in length, and there is the occasional trimming to keep it tidy so that also slows the proccess.
At the speed mine grows... well over a year I'm afraid :o I trim it every 3 weeks or so but than no more than 1 to 2 mm comes off. Extrapolating that would mean about 1.5 to 3 cm of hair growth per year. If I'd start now you'd have to be veeeeeeeeery patient Sally :D
I'm currently trying to grow one. I keep it maintained though, as it grows. So that it doesn't look scraggly. It's taken me 8 years just to get basically a goatee and a little bit of my sideburns/cheeks (I don't shave that often, just keep it trimmed). The more you shave, the faster and quicker it comes in. I just don't like doing it