I recommend preparing the Pico de Gallo and Guacamole first. Store them in the fridge for now.
Next prepare the Taco Meat, and Refried Beans and keep them warm on low (in separate pots / pans on the stovetop).
After that, prepare the Nacho Cheese. I like to do this last as it's best as fresh as possible.
You can heat up your chips in the oven if you like, but I usually don't. I'll lay them flat on a plate with minimal overlap so each chip is fully loaded.
First add some refried beans to the chips, then the meat, cheese, pico de gallo, guac and then sour cream!