As I judge the shows, I am surprised by the number of birds that are so nervous that they flap their wings and some carry their wings poorly letting one or two wings drop.
It is important to feed a show bird a reduced calorie diet. Feeding high fat seeds just gives them too much energy to stay relatively calm in the show cage.
Even if you only have a couple of days till the show, you can make a big difference by feeding only water with Purina Canary Finch Mix. This product calms and is the very best at correcting poor wing carriage. It is sold at Petsmart and my store has it marked down till the end of November to $6.49 for two lbs. instead of $9.99. They will waste the white millet but what they eat is of superior nutritional value! It is excellent for improving confirmation. Should you have thin Borders get some of the Tropical Snack Mix by Purina. It is very good nutrition but also the dehydrated fruits are very fattening. They do waste some of it and the only birds of mine that take to it well are Borders and Columbus Fancy.
My second choice is feed water and plain L'Avian Plus. Also a fortified seed and at $35 per 25 lbs, it is a mix that you can feed a large aviary.
When using vitamin fortified seed, it is important to remember that adding regular seeds to the mix decreases the nutritional value of the mix as unfortified regular seeds are deficient in a number of nutrients. Using the mix as it is brings the best results.
My third choice is straight canary but you need considerable vitamin supplements to improve the confirmation like the fortified mixes do.
Even with fortified seed mix, I use extra vitamins in the water. Now I am using the dog vitamin Boost but others such as poultry vitamin/electrolyte, or vionate dog vitamins or other vitamins will work. If you use those with amino acids you may get breeding condition (cocks flapping their wings) so it is somewhat easier to use the plainer kinds of vitamins at this time of year. Birds that are in top condition show better confirmation.