Directed by: Tim Burton
Starring: Johnny Depp, Winona Ryder, Dianne Wiest, Anthony Michael Hall
Continuity mistake: When Kim is watching Edward cut the roses, in closeups she's quite close to the curtain, and it's hanging straight down. In the wide shot she's slightly further away, and the curtain is angled outwards because she's holding it back with her hand.
Continuity mistake: Before Edward is looking at the family pictures you can see some scars on his face are open, when the camera focuses back on him the scars are closed.
Answer: As the other response says, the number of years is never stated. Physically, I think he is supposed to look about twenty years old. Bill wants him to start a proper business. None of the adults seem to think that he should be in school.