A Power of Attorney gives you the power to grant another individual (your agent) authority to act on your behalf. You can grant your agent broad authority to act in a variety of situations, or you can be very specific. Ordinarily, when you execute a Power of Attorney, the authority is granted to your agent immediately. However, in the same way you can be specific about which authority is granted to your agent, you can also be specific as to the timing of when they have this authority.
A Power of Attorney can be a very helpful tool. The attorneys at Jarvis, Bridge, Halttunen, & Weyer, LLC can let you know if a Power of Attorney is right for your situation.