Completely agree on that you wait as long as it takes. But my experiences with both TM and RS is that they are both really quick at putting out TK-kits. My TM kit took about 1 month from initial contact, and a garrison mate (the kit I built last summer) got his kit from RS shipped within two weeks.
As for replacements, I can only speak of TM, but I had mine made quickly (once TM remembered to make them. A friendly reminder was all it took). Maybe two weeks all in all.