This an old age tradition. On Purattasi Saturday, we light maavilakku in our homes, and invite Lord Malaiyappan(Tiruppathi Perumal) to visit our homes and bless us and give darshan to all of us in our homes in the form of "JOTHI". This is indeed a great experience every year. We do not light the maavilakku during Brahmothsavam in Tirupathi as HE will be busy there and also we do not light it on "Mahalaya Paksham". So, one or two Saturdays will be left over and we have to light maavilakku in that day. If no saturdays are left, then we can light the maavilakku on Aipasi 1st saturday. Nobody will eat till the LORD REACHES HIS ABODE(TIRUMALA) and this is called "Malai Eruthal". All of us chant Venkatesa Suprabatham and other slokas of the LORD during this festival. More at
http://shanthisthaligai.blogspot.in/...a-vilakku.html
http://shanthisthaligai.blogspot.in/...a-vilakku.html