The fact of the matter is that most roleplayers who use this site work. I include those attending school, college, university, etcetera in that estimation. Working while also roleplaying is not a special, unique qualifier - despite how people might treat it otherwise.

The simple answer is to make the time for it that you want to make for it. It can be tempting to approach it on a 'do what I can with whatever time I happen to have' stand, but that tends to make for inconsistent posting. If you treat roleplaying as a hobby, do it during your free time. If you are a touch more serious about the whole affair, plan ahead and make time for it in your schedule.

Either way, only devote as much time to it as it is important to you. Take a step back and evaluate how much it means to you. Do not try to write according to your expectations - write according to how rewarding and enriching the experience is to you. If that makes any sense.