No, you cannot oversalt a dish simply by adding salt early in the cooking process. The total amount of salt determines the saltiness, not when it's added.
The perception of saltiness in a dish depends on the overall concentration of salt relative to the other flavors. Adding salt early allows it to dissolve and distribute evenly throughout the ingredients. This can actually *improve* the flavor by seasoning the food from the inside out. Some chefs prefer salting early because it helps draw out moisture from ingredients, which can enhance browning and develop deeper flavors. The key is to taste as you go and adjust the seasoning accordingly. If you add too much salt at any point, early or late, the dish will be too salty. It's the *amount* of salt, not the *timing*, that matters most.
Always taste your food frequently throughout the cooking process. This allows you to adjust the seasoning gradually and avoid accidentally adding too much salt at any stage. Start with a small amount of salt and add more as needed, rather than adding a large amount all at once.