Heya, Groshnik! I already told you it'd be an actual 24-hour day, by Crom's teeth! ;-)
But, yeah, I can see the actual ritual being maybe 12-16 hours or so, with the final arrival of the bonded animal rounding out the 24 hours.
I've always preferred a more natural, intuitive interpretation of RPG rules anyway, as long as the spirit of the setting is maintained and everyone is having fun without taking undue advantage of any "holes" in said rules (or the GM or the other players, for that matter).