We have phillips battery operated timer on our christmas wreath. It has no instructions, only a timer switch. The only info on it says it is 6hrs on, 18hrs off. How do you set it to go on at 5pm?

Many of the smaller timers are light activated solid state and will go on at darkness and run for a short period. Otherwise the batteries will be used up..

If you notice the "switch" for this wreath has three positions: the middle is position is off, to the right is on, and to the left is the "timed" position (should have a T at the top). You are correct that in the "timed" position that the lights will stay on for 6 hours then off for 18 hours... and will stay that way as long as switch stays in timed position. So, if you want the wreath to come on a 6 PM (and go off at 12 PM), wait until 6 PM and then turn the switch to the timed position (from the off position). If you wish to "reset" this to 7 PM to 1 AM, you must turn the switch to the off position and wait until 7 PM and then switch to the "timed" position. Got it?