There is no hard and fast answer to these questions, however, we always recommend that you review your will (and trust documents if any) at least annually. You miht be surprised at how difficult this is to do since such a review is easily forgotten. If you need an effective way to schedule this review we suggest that a good time is immediately after you have filed your federal income tax return for the simple reason that you will probably have a good grasp of your personal financial matters at that time. However, any method that consistently helps you remember to review your will etc. is fine.
Upon review, it will probably be obvious whether any changes need to be made. In particular, if you have had a child in the past year, if there has been a substantial change in your family’s current or future earning power, if you or your spouse has received a substantial inheritance or any other event has occurred that could alter any principal provision of your estate plan you should consider a revision. The expense of such a revision will usually be substantially less than the cost of your original estate plan, and in any event, cost should not be the final determining factor.