Just to expound on the ammonia in the bag during shipping, when a fish is shipped in a bag, the respiration of the fish produces CO2. The CO2 increases the acidity of the water and causes the pH to drop, thereby, allowing the ammonia being produced from the fishes waste products to convert to the much more harmless ammonium while the fish is in transport.
The problem you have is when you open the bag, it allows for the pH of the water to start increasing as the water aims to reach atmospheric equilibrium. This causes your ammonium to convert back to toxic ammonia in the bag and causes major issues with the fish very quickly. If you drip acclimate, you're introducing high pH water to the bag which increases the pH even faster and the ammonia gets toxic even more quickly.
The ideal scenario is to open the bag very quickly, disturbing the air in it as little as possible to pull just a little water out to determine the salinity of the water, which is usually 1.018-1.020. Heck, you may even just poke a hole in the bag to get just enough water for a salinity measurement and then tape the hole back up. Then temperature float the bag in the new water, match the new water salinity to the bag that the fish is in, and once temperature matches, literally put the fish right into the new water with matching salinity and temperature. No drip acclimating, just right in. Fish are active osmoregulators and can readily adjust to salinities that are within +/- 0.01 of each other.
This allows the fish to bypass the toxic ammonia issue when being in the bag too long. This really only applies to shipped fish. The ones you buy locally have not been in the bag long enough to produce that much ammonia so drip acclimation is still ideal.
Hope your fish makes it. I know the information above is irreverent for you now but I wanted to post for future reference for everybody else.