1 Corinthians 16:2

Upon the first day of the week let every one of you lay by him in store, as God hath prospered him, that there be no gatherings when I come (KJV)

Then: What Paul wants is to have everything collected before he arrives. Before, he's never wanted money to be part of his ministry because that would skew the message of Christ's forgiveness. If everyone knows ahead the collection is for other church's and the process completed, Corinthians are less likely to think about Paul as one who asked for money. Wright (p. 231) also notes that Paul was also removing any bases of possible accusations of fraud.

Now: Believers have used Paul's plan in the churches for many years. The sacrament of giving is a traditional part of serving God. A recommended tithe of ten percent is based on Old Testament teachings, but the amount is always a personal commitment between the individual and the Lord.