Average age of accounts is a pretty big factor in credit scores. Every bank will probably have its own proprietary rules for deciding when to offer credit, but

Average age of accounts is a pretty big factor in credit scores. Every bank will probably have its own proprietary rules for deciding when to offer credit, but the credit reporting agencies who generate a number use fairly well known criteria. Amount of credit, number of accounts, payment history, percentage of credit used, age of accounts, diversity of types of accounts.