I never said it's bad to have a job. It's just that it'll be better for you to tell people "I can play on D day at T time, does that suit you?" - and that, until both your opponent and you agreed on a date. If something comes up at the last moment, after the date arrangement, warn your opponent, and arrange another date. Game arrangements don't take long usually - I can do them just fine, and that, even though I have school (and school days are really long here in France).