At least the first scapes on a substantial proportion of daylily cultivars are formed the year before they bloom. I have never seen any research about when rebloom scapes are formed. My opinion is that rebloom scapes are formed after the first scape (as opposed to at the same time as it) and probably in the same year that the rebloom scape normally would bloom.
Daylilies that flower late in the bloom season appear to not have their scapes present the year before.
