Table Service credits are not exclusively dinner.....so what I'd do if I had an extra CS and TS credit is:
Morning after you arrive....start your trip off with a fun character meal (these are 1 TS credit)....my favorite is Crystal Palace with Pooh and Friends...if you make your ADR for before the park opens you get the fun of walking down Main Street practically alone, can get some great photos in front of the castle without others in the background, and the food is pretty good. There are lots of other character meals too in case Pooh isn't a favorite. If character meals in general aren't your thing, Kona Cafe at Poly or Boma at Animal Kingdom Lodge are delicious breakfasts as well.
Then....later that day use a CS meal for lunch.....and schedule a late dinner at a TS restaurant of your choice.
You've now used your one extra TS credit.
Then on another day I'd use my extra CS credit for a quick breakfast somewhere.....perhaps at your resort....or at France's Boulangerie Patisserie (this would also be a great treat anytime of day). The Norway bakery also has some great food that can either be a sweet breakfast or a yummy treat later in the day.
The extra snack credit is also easy to use.....keep in mind that if you're not an everyday snack person that you can use these at Goofy's Candy store in DTD. Many people go here on their last day to use up their leftover credits with treats that they can take home to keep the magic going a little longer, or to spread the magic to folks at home.
Rather than think of it as 1 TS, 1 CS and 1 snack credit a day....which makes many people feel they HAVE to use all 3 choices each day....think instead of your entire trip....if you're staying 7 nights than you have a pool of 7 TS, 7 CS and 7 snack credits. You can use them whenever you like....they're good from the moment you check in, until MIDNIGHT on the day you check out (so even if you have to check out at 11am, but your flight isn't until evening....leave your luggage with the front desk of your hotel to hold for you, go to the parks, enjoy a few last minute rides/shows, use up the last of your credits that day, return to your hotel to pick up your bags and depart for the airport. I always make my flight home late late in the day.....so I have a few last hours in the park, I can sleep on the flight home, lol.
Have fun! And don't sweat too much over flight changes....they happen, you adapt. Always check though....often the people doing the flight changes simply put everyone on the flight that is least booked at the time, not really giving much thought to the fact that if you booked a morning flight you probably won't be happy with an evening flight.....their goal is simply to clear that flight of passengers and get you on another flight to your destination. BUT....you CAN call them after you are moved and request another flight better suited to your needs....if there is space available they'll move you to that flight instead, so it's very possible your change can be minimally distruptive.
Even if it was no big deal to miss the first night...I don't think I could get into even a "two credit" dinner for 12 of us for dinner (in order to use up the credits)...I think what I might do is just get the meal package for five days...and plan on just making regular reservations some place....If our plane was real late...we could cancel the reservations for that first day and just eat counter service and just pay for it...
and if the Dinosaur Restaurant is open...We could still go there...Our large group isn't going until February...and it said the restaurant looks to be open in the fall...Hmmm...all kinds of choices now...that I didn't think of...Thanks to my fellow Disners! 
