A poor fund of the surviving data on princely assemblies which had played an important role in political life in Russia since 11th century is well known and was scrupulously studied. The analysis of exact dates of their holding opens new possibilities in studying the Old Russian princely congresses. This approach is possible in the light of the practice widespread among the secular and clerical elite of Rus’ to combine the most important public ceremonies, including princely ones, with church celebrations of the weekly and annual cycle of services, and also to avoid them during certain periods and days of the church year. The sources of the pre­Mongolian time refer to 14 exact dates of princely gatherings in the second half of the 11th through the first third of the 13th century which allow us to reveal a connection of these events to the days of week, to the significant landmarks of the church calendar, and also to the name and funeral feasts of representatives of the ruling dynasty. The examination of the data, carried out in this article for the first time in historiography, allows us to speak of a stable tendency to appoint princely congresses on the eve and/or on the very day of one of the great feasts, an honoured church celebration on a smaller scale, a Sunday or one of the “princely” days listed above. In some cases, there is an overlap of these “calendar strategies”. This state of affairs suggests that an essential element of the ceremonial of the princely “snem” was the joint prayer of its participants during the solemn service, which not only spiritually consolidated the unity, but demonstrated it to the contemporaries. Perhaps it was during such a service that the mutual oath (the kissing of the cross) was taken if the princes reached any decisions, binding them to further joint action. The results of the study are interesting in terms of characterizing the ideological component of the princely culture of pre­Mongolian times and the temporal culture of Russia in the first centuries after its baptism.