Way back when Naruto first learned the Summoning Jutsu. How long exactly did it take him to summon Gamabunta? It seemed to me that it happened over the interval over 2 days at most.
Something like 3 days; Jiraiya pushed him to a slippery cliff to make him summon...It would be an interesting twist if Naruto did not come off and Jiraiya said "oh well...guess he is not the one" and continued his journey.