Find the first financial threshold period

The balance of a savings account starts at $8,000

Each year, it grows by 6.0%

Use the stated constant-rate model with no deposits, withdrawals, repayments, fees, additions or disposal during this interval. The starting amount is at index 0 and each update is one stated period

Keep model values unrounded when deciding the first crossing. Round only a requested final amount as directed; the stated percentage is already per period