Well maybe it’s a bit more than a day, but even so, waiting just a few days before smoking a new arrival will improve the flavor of a cigar. This is, of course, dependant on the cigar being properly cared for while “resting”.
Waiting a month is even better. During that time, a cigar’s flavor will coalesce and become more compact. There are various explanations for this, but I think it is largely because the cigar has been properly conditioned before smoking, a critical factor in how a cigar will taste. But for whatever the reasons, the result of a little delayed gratification is often a better tasting cigar.