Heh, my Japanese classes started with about 30 people and windled down to about 7 by the end of the semester as well. I remember one class when it was near the end of term so some people didn't bother coming, and so with the lecturer, assistant lecturer, and the two extra helpers (one 4th year and one Japanese guy) they outnumbered the students. And then there's my chinese one where I went into the second year class in my first year and now I'm the only person left doing the upper level chinese units.

Basically the question is whether you mean you can do one chapter per week, or whether it will take you a whole week to do a single weekly chapter. For most translators you wouldn't want to spend more than about 3 hours on a weekly chapter, and that's if it's a really wordy manga or if you are working pretty slowly anyway. E.g something like Bleach could be done in half an hour, while something like Gintama probably takes several hours.

That said don't let that get you down, when you first start translating it will take you a lot longer as you need to use the internet to translate words instead of just recognising them off the bat, but eventually you will start to remember how to read the kanji (if not write them) and it will start to get faster as you go along. Translating manga is seriously one of the best ways of studying Japanese I have found. The thing to note though is that if you are looking up every second or third word then you probably might need a little more study first.

I guess a little test would be good. Get a manga series you want to translate and translate the first few pages then post them here and a link to the raw you got them from.