I always look at what's last minute as people change their plans all the time. I just looked for tomorrow night, party of 5. I saw BOG, Liberty Tree, Storybook, Chef Mickeys, California Grill. Hollywood and Vine, Garden Grill, Ogas, all decent times, all party of 5. Most in the 5:00-6:30 range. Don't despair, just keep checking and always look for last minute while at Disney!
Try both 5 and 6 people. One time I wasn’t able to get 6 for garden grill but I could get 5. I tried and tried but couldn’t get that 6th not even with a modify. I did well with the search last night using 5 people as I noted above and those were just the more popular ones that were available. There were also restaurants like the Plaza, La Hacienda, is Napoli etc available