It's fine either way. 5 weeks is a SAFE bet. If you fail after 5 weeks then you're body is screwed.

As to your working out, depends. How much of a sweat do you break, how much do you weigh, how much fat do you have on your body?

I'm not trying to embarrass you or anything, but if your body is flabby or whatever, you retain metabolites a lot longer. Another one of my female friends could go on an 5 month binge and pass a piss test in 2 weeks. I'm extremely jealous of her....