Whenever I built a boat, I would put a coat of varnish on it and use it often a few days later. I paddle a few times a week and perhaps the following week I might give it a wet sanding and put a 2nd coat on. My point is that once a first coat is on there, putting it in the water in a few days will not bother anything. You don't have to put the boat in a display case throughout the varnish coats.

Also for conversation: I was at a boat show once admiring some "Windsong Canoes" with these mirror like varnish jobs. Upon asking the builder, he told me he puts coats of varnish on one after another as soon as the varnish is dry to the touch, just building up a thickness with a few drips, bugs on it etc. Then after 4 or 5 of those, he lets it harden and sands and puts the final coat on.