Leap of faith

Zooming right along here, and I've gotten to the point of sewing the Rambling Rows Jacket together. With this pattern, you knit it in one piece, sew the underarm/side seams, then add the borders. I'm going to block it only after all the knitting is done. But I couldn't resist trying it on at this point, and that was probably a bad idea because it's too small. Okay, I knew that going in. It should be too small before blocking because the gauge swatch promised me that once I get this sweater wet, it's going to grow. How much?, Well, let's hope that gauge swatch was accurate. And can I just say that knitting two sleeves with only a vague idea of how long they're going to be after they're blocked requires an inordinate amount of courage?