I think the instructions for my pygmy coho recommended using the kayak for a few weeks (or months?) before sanding and applying the varnish. Anyway, I did that and I don't regret it.

I did the same thing on the CLC 16LT that I built this spring. I've had the boat out in intense sun for about three weeks. The color did darken a bit where it was exposed, but I like the new color better. The only problem is, as was mentioned, the tan lines on my hatch covers. I still don't regret taking the boat out before the final finish, but I am working on the varnish now.