Currently Being ModeratedJun 3, 2013 8:44 PM (in response to Marcus Merritt)
Time Machine backs up hourly, if your Mac is awake and the destination is available. Let it. If the destination isn't available, it can't back up, so it will say "delayed."
Leave the backup drive on and connected to your iMac. That's how it's designed to work, and will protect you best.