Ekadashi in the full moon fortnight of Karteeka month is called Prabodhini Ekadashi. Lord Vishnu wakes up after a four month long sleep on this day. In north India people avoid all types of personal customs like entering new houses, thread marriage, marriages etc. Monks go through the four month sacrifice which is well known as chaturmasa vrata. According to the sacred works one should pray Vishnu to wake up for the sake of universe. The intermediate time of Ekadashi and full moon day is a sufficient time to take Deeksha of new mantra etc.
Lord Vishnu goes to sleep on the ekadashi of the full moon fortnight of the lunar month Ashadha. Starting from that day people avoid initiation of all works and they believe that the same may not get the wishes of Lord Vishnu. One of the definitions given to lord vishnu is " viswa vyapaka seelatvat vishnurityabhidheeyate" That means the element which occupies the whole universe is called vishnu. lack of the availability or positivity of that element works or ambitions may not be fulfilled. this definition has been given in the 'Agama' which control the temple culture and its origin is in the Veda, the oldest literature of this universe