I'd imagine there are many factors to consider, such as which semester you usually do best in (for example, you may study particularly well or unwell during Christmas holidays or Easter holidays), or such as what are the other modules you will be taking (for example, it could be the case that there are four modules you like in one semester but only three in another), and possibly there may be more factors. Without more information about your case, I don't think we can give great advice.
Personally, though, I would do it in the second semester, but I would work on it during first AND second semester (and perhaps summer?). This way, you'll be able to commit more to the project - a project, in my opinion, requires more commitment than the other modules. But this is just my view. It would be better if give us moire information about the situation.