Changing your strategy applies to future contributions and takes 1 to 2 payroll cycles. Your existing holdings do not move until you rebalance.
A rebalance into individual shares end-to-end typically takes 10 to 15 business days.
If you see ‘Can't rebalance, transactions in progress’:
This means that a rebalance cannot run while trades from a recent paycheck are still settling. Those usually clear in 3 to 5 business days.