What are the things I can eat during the 1st week of having dentures?

Soft foods. Soft foods while you learn a new way to chew. Dentures require learning to chew by grinding in very small circles with food on both sides at the same time. This takes practice. So, start with things like : applesauce, yogurt, pudding, eggs, bananas, mashed potatoes, noodles, soups, etc. Graduate to soft toast, finely chopped ground beef / turkey/ chicken, and fish. Be patient and eat very slowly.
Comfort is the guide. If you have had teeth recently extracted, or are wearing dentures for the first time, or wearing a new set of dentures, the fit of the dentures and the ability of the gum tissues to withstand chewing forces will dictate which foods you can eat comfortably. The key is to stay nourished.
Many options. Learning to eat and speak "normally" with new dentures can take several weeks or more, so patience is key. Stick to a softer diet, cut food up into smaller pieces, and try chewing on both sides of your mouth at the same time. It's like anything new...Practice makes perfect!