I would stay at POR for that first night. I would even tag my bags with the yellow tags. Pack a carry on bag with whatever you'll need for that night, and possibly the next morning.
You can go to the resort, relax, check it out, maybe swim.
I wouldn't worry about attaching tickets to the first night stay, unless you really want to head to a park. But, sometimes it's nice to just get to the resort and relax for that night.
The next morning, you have a few options...
1. Have Luggage Assistance move your bags to the new resort....it will take until late afternoon/early evening before you get the bags though. Then just take a bus to a park and after lunch, head to the new resort to get checked in.
Or....
2. Just take your bags, and get a cab(s) to the new resort. If your room isn't ready, leave your bags with Bell Services and go to a park.