Step #1 is to write out an investment policy that defines when you will review your allocations. It is best to do it on a plan.
Some will argue that it's best to do it annually or every other year. Others say you should do it once your portfolio gets out of balance by a certain percentage.
My opinion is that it doesn't matter a whole lot, as long as you have a plan that you're consistent about.
I personally have different policies for different accounts. They are:
1. My IRA's and current 401k: Reviewed and rebalanced annually.
2. An old, large 401k: They send me a notice to re-balance anytime the portfolio is out of target-allocation by more than 5%.
3. My taxable brokerage: I add a lot to this account every month, so I buy new shares in a way that always moves my portfolio towards the target balance.
