I think the parade time varies depending on the time of year/park opening times, but is usually either at 3pm or 3.30pm. No doubt someone else will know. Either way you should have time to see it prior to your PS if you find a spot close to CP, but you will need to stake out a place early - it's a popular place from which to watch.
The parades at MK always used to alternate start points (i.e. starting from where the previous one finshed). I'm not sure if this is still true. If the parade starts at the fire station on Main Street, you will be fairly close to the start. If it starts next to Splash Mountain you will have longer to wait. In that instance, a 3.30pm start time would mean that you may not get to your PS before 4pm (although you should get there <i>by</i> 4pm), but that won't be a problem. Although they ask you to arrive at the podium 15 minutes prior to your PS time, we only ever do that if it fits in with our plans. That's the beauty of the PS system - you get the next available table after your PS time (or arrival time), so you won't be keeping anyone else waiting.
Once you are in the park you could ask a CM where the parade will start and then stake out a spot as close as possible to that. If it starts at the Main Street end, you could then follow it up to CP. If it starts at the SP end, you could stake out a spot in Frontierland and, when it has passed, hop around the back through Adventureland to CP.
