Sure, go ahead and start the sweater even though you only know where the first skein of yarn is. The other one will turn up before you need it.
Sounded like a good idea that the time, but now I'm almost out of yarn and the second skein isn't in the bags of nice cheap acrylic or anyplace else I can think of. I could stripe the yoke with the leftover yarn from Heath's Weasley Sweater, but I don't really want stripes. I could go to Michael's to buy another skein of the same color, but I've really got no business going back and buying more yarn after Wednesday's little adventure.
At least I've got some options, I just don't like any of them. And I'm anxious to finish the yoke and see if it fits, especially after all of the math I did (with the help of the JWS Top Down Yoked Percentage Sweater, but it was still math!) to figure out the decreases.
I didn't expect to make it this far this quickly. I was sure I'd trip over that skein of yarn long before I needed to go looking for it.
Now I need it, and the odds of tripping over it are very slim because the sewing room is really cold and really dark and I don't expect to spend much time up there until the weather warms up.
Maybe I'll keep knitting and hope there actually is enough yarn in the first skein.