You don't have to do anything to be a hopeful, technically: your character without a master is pretty much defined as a hopeful (assuming you're talking about the Jedi). Training tends to span over a short period of in-character time (since the actual process takes a lot longer than we like) before Knighthood, so close to adulthood is what is generally accepted.
Everyone assumes all Padawans are promoted at 17, 18 or 19.
NONE were.
An appropriate age for a Padawan on this site (as they don't age from training to Knighthood in RP) is early twenties. Or if you really want your teenager, then have the teenager but when they're knighted bump them up to their mid twenties.
Very well.. I was just thinking about the movies and the age you become a padawan in... but I am not assuming that we're suppose to play 6 year olds so I was curious