Many Baptist churches have communion of the Lord's Supper the first Sunday of the month, so take the Supper once a quarter. I suppose it would be a tradition in some Baptist churches, but I would not think it was a "Baptist" tradition.
I think those who have a schedule time to take the Lord's Supper simply did it at these times for convenience or to regularly schedule it so people would know when the would take communion. Although it is not "scriptural" there is nothing unscriptural about taking the Supper on a regular and scheduled basis. Some church constitutions state the church will have communion on a specific day and time.
I have never scheduled the Lord's Supper as many Baptist churches have. The reason is that in many churches that have this practice the Lord's Supper becomes a ritual and people tend to lose their understanding of what it is and why the Lord told us to do this. It becomes a routine and loses its purpose.
The following is information about the Lord's Supper you might find helpful.
The Lord's Supper is a memorial meal initiated by the Lord Jesus Christ on the eve of His passion, symbolizing His death and blood atonement for sin (Mt. 26:26-28; Mk. 14:22-24; Lk. 22:19-21; Jn. 13). The Apostle Paul plainly tells us that the Lords's Supper is a memorial ("this do in remembrance of me"--Lk. 22:19; 1 Co. 11:24,25) and a picture ("ye do shew"--1 Co. 11:26). The Lord's Supper is to be practiced in the church (1 Co. 11:18,20,22,33,34). Each church, as the body of Christ (1 Co. 12:27), is to observe the Lord's Supper after the Scriptural order. The church is responsible to oversee every aspect of the work of God to maintain doctrinal and moral purity (1 Co. 5:11-13; 2 Th. 3:6; Tit. 1:9-13; 3:10,11). We, therefore, do believe the church has both the authority and the responsibility to restrict the Lord's Table. Those who observe the Lord's Supper privately apart from the church are ignoring the Bible pattern.
The Seven-fold benefits of the Lord's Supper: (1) In 1 Co. 11:28 there is Examination. But let a man examine himself.' (2) In that frame of heart we then are to eat.' That is Participation. (3) Thus the supper becomes a Proclamation of the value of that wondrous death for poor sinners (1 Co. 11:26). (4) The feast is to have Continuation. But how often? [The Bible does not say how often; it simply says "as often as ye eat"--1 Co. 11:26.] (5) Anticipation is a hall-mark of the supper. Till He come' are words that remind us that the supper is not only retrospective, but prospective. (6) Of course it is primarily a supper for Recollection of the Lord in His suffering and death for our sins. Such continual remembrance ought to stir the heart in love to the One who died for us. (7) A proper preparation of heart beforehand, and a right attitude at the supper will lead to Adoration. In remembrance of Me,' said the Lord. The word translated worship' in the N.T. means to kiss towards.' It bespeaks an attitude of love, of obedience, of allegiance, of adoration (The Church of God: A Symposium).
Requirements for taking the Lord's Supper: (1) The individual must be a born again Christian (1 Co. 10:16-17). (2) The individual must be a baptized member of the church (Ac. 2:41-42; 1 Co. 5:11; 11:20,33-34). (3) The individual must be in fellowship with the Lord (1 Co. 11:27-31). This involves striving to live in obedience to the Bible and carefully confessing one's sins (Jn. 8:31-32; 1 Jn. 1:5-10).
Restricted Communion: Some object to placing restrictions on the Lord's Supper, saying we have no right to restrict the Lord's table. But the Bible teaches differently. Following are ways in which the Bible gives clear restrictions in this ordinance: