But if we look a little more there seems to be a connection between завтра and завтрак, with both related to the root for 'morning' - Fasmer's etymological dictionary gives comparisons to some other Slavic languages
Assuming this sentence is a greeting, (there wouldn't be the exclamation point otherwise), its English version should be "See you tomorrow !". "Until tomorrow !" is a greeting too ? I' ve never heard of it.