About D4 visa

As far as I know, the money needs to be in the bank account for six months before applying for the visa. However, I want to know if the total amount needs to be there for the entire six months, or if I can deposit a small amount each month starting six months out, so that the full amount is in the bank by the end of the sixth month for the visa process. Also is it acceptable if the sponsor is taking money from somewhere else to deposit it in the bank.