Rimwolf and Kugai, I'm not convinced and had written a pretty large post about it, but I went back and used Dora's hair as a measure -- she talked about growing it out in 1302 and by 1311 she's showing a good month of blond growth, maybe more (it's hard to judge with cartoon characters). So, I'll give you that at least a month, but not more than two, has taken place between 1302 and 1311, but we don't know for certain when 1307 took place in that time -- weather isn't a good indicator since Jeph doesn't keep a strict seasonal year in the comic and weather tends to show up because he wants to do a gag. Dora doesn't show up in those strips, so for all we know that conversation took place just days before everything else started happening, even a couple days before the snow started.
The Dora Hair Time Measuring device (I wonder if I can patent that?) is not the best measure, since she's a toon and her hair length is whatever Jeph feels like drawing at the time. Whatever we do there, we are working with assumption, because we don't see Faye and Sven together much in that time period either. No one else's hair seems to change except Sven's, which gets shorter. It's just barely a good measure. For all anyone knows, Dora dipped her head in bleach.
It's not enough to judge Sven and Faye as having reached "coupledom" in any case. There's nothing in the strip to back it up -- it's all assumption on our part.
I'm still pretty amused at myself for going to all the trouble of working this out, but it was fun!