John Calvin Commentary Luke 2:44

"but supposing him to be in the company, they went a day`s journey; and they sought for him among their kinsfolk and acquaintance:" — Luke 2:44 (ASV)

And thinking that he was in the company—Many passages of Scripture show plainly, that those who came from a distance, at the festivals, to worship in the temple, were accustomed to travel in companies. There is no reason, therefore, to wonder that, on the first day, Joseph and Mary were less anxious about the child; and their subsequent conduct shows that this was not owing to indolence or carelessness.