You can change your portfolio allocation no more than approximately once every five days. This is because, when you change your allocation, it requires us to sell and buy shares in your account to rebalance your assets to your new allocation. To make sure your portfolio change is correctly and efficiently processed, we need at least five days to complete the process.
However, it is best practice not to make frequent changes, as your portfolio is meant to be for longer-term investing. Changes should not be made more frequently than a few times a year, because the allocation reflects risk parameters, which should only change if your preferences or financial situation change.