Spoilers? I don't think there's any plot twists or anything...
It took me less than a week and was around a year ago I think. It was the first time I ascended and the last time I played, hehehe... Being the "can't-stop-playing" species of man, I played practically nonstop for that week or so, sleeping after each character dies and then continuing on.
If you want some more advice, the first 10 levels are going to be the hardest ones. It might be tempting to choose a brawler class like valkyrie or samurai because they make those really easy, but the long run for those classes suck balls. Spellcasters like wizards and monks have a really hard time early on but once you're a good way in, that level 20 wizard can smash through thousands of guys without breaking a sweat. Same goes with monks and priests.
Also, it can get really tedious later on as you farm for the best equipment like say... +10 BSM or something, so prepare yourself.
As a businessman, unnecessary risks are annoying. That's why I'll advise you to actually not wish for anything from fountains or sinks or whatever. In fact, if you're a wizard, you're probably going to want those things so you can get holy water or blank scrolls.
Lastly, once you're on the home stretch, heh.... things get really, really hectic. Make sure you are prepared because it's stupidly difficult and one false step means doom.