Well when you get off the plane.. you'll get to ME. From several trips, we know exactly where ME is, but if this is your first time--then plan a few minutes to stop and look for directions. The ME line has taken anywhere from 10minutes to an hour for us. There are up to 3 resorts to stop at on an ME bus. If you are the last one, expect to add quite a bit of time. You will then check in--sure it helps to do online check in, but there still may be a line, then you have to go to your room... which at POR can be quite the hike away. I'm sure you'll need a few minutes to settle. Then you need to get to your bus stop and wait for an EPCOT bus. Depending on your bus stop, there may be 3 others to stop at and pick up others. Get thru bag check at Epcot and go allllllll the way to the back which is another hike.
LeCellier is booked at capacity at lunch because it is only 1 credit and people can get a filet. They may not be able to honor a late showing for lunch. We tried it twice and disliked not only the food, but the service both times (only tried it again because we were hoping it was a fluke--we do the DxDDP). There is no comparison to the California Grill which is an amazing experience and meal. You will be rushing and although you said canceling wasn't an option--it really is the best option. POR has a nice food court you can pick up something light--or take the boat to Downtown Disney so you can really enjoy your California Grill experience.
I wouldn't want to start my vacation off on a rat race--and neither do the people who travel with me.