That's what spooks me the most--off gassing. I have some pre/post cat conversion varnish that offgasses horribly for about a week then you can't smell anything after that. I can still smell the wipe on poly 3 weeks after application.
I was already planning to line the back of the drawer front with spanish cedar anyways, maybe I should just do it all in SC.
Makes me wonder what Forrest uses for his hardwood faces on his drawers.
Since we all test our finishing schedules anyway...right?
right? 
...you could wax a middling size scrap, let it cure out for 2-to-7 days, then seal it in a plastic bag for say, 24-48 hours to concentrate any residual off-gassing. Open. Sniff. Repeat until you detect nothing or you give up on the smell going away. Might work.
Back to shellac, I don't think you need worry about off-gassing...with caveats. The shellac itself is nontoxic and has no odor to speak of but the solvent sure as heck does. While the Bullseye aerosol shellac contains some petroleum products in the propellant, the solvent itself (and same for the canned stuff) is ethanol and isopropyl alcohol, which flash off pretty darned quickly...say, 24 hours or so for a typical thin application. If you mix your own from flakes, though, you might want to take care which denatured alcohol you use. In addition to ethanol, some of the home center flavors like Klean Strip in the blue/red can also contain 40-60% methanol. At the other end, Klean Strip Green contains <5% methanol and some folks on woodworking forums I frequent report that flakes dissolve more readily in the higher ethanol concentration. As far as I know, methanol off-gasses similar to ethanol but it does pose a significant neurological hazard during application, via skin absorption and inhalation. Typical precautions like good ventilation and protective gear are adequate but in my book, less icky stuff is a good thing. As I hinted upthread, though, you can avoid methanol altogether by using pure (or nearly pure) grain alcohol...and drink what you don't use.
