I just started playing again two weeks ago. I had a level 25 archer at the time and I only get to play around 2-3 hours a day. After two weeks I now have a 50 Bard and pretty much all crafting/gathering classes started (all between lvl 5 and 20). I just hit 50 two days ago so I have no idea how long it will take to gear up and complete all post 50 content, but 2 weeks is easily enough time to get a single class to 50.