Another thing to consider is if you’re willing to have lunch without some of your party if necessary.
Some Disney restaurants do refuse to check in a party if everyone’s not there. However, you will not be charged a no show fee if at least one person shows up, even for parties much larger than yours.
Since you’re arriving at different times, I don’t know if you’re planning to leave the airport together or separately. If you leave the airport as you arrive, those who come in earlier could go to WCC and talk to the people at the check in podium. If any travel delays happen for the person getting in last, you can let them know the situation and see if they’re willing to work with you. Worst case scenario becomes that they refuse to work with you and whoever’s late doesn’t get to eat lunch. I find that very unlikely, but it is a possibility.
While it was years ago, in my experience working as a greeter at a Disney World restaurant (Tony’s Town Square), we were FAR more willing and able to work with people who made the extra effort to talk to us, especially in person. So, if at all possible, my recommendation is always to show up and let someone know the situation.