Swapping out a shallow sink and leaky tap changes how your kitchen works every single day. Deep sheet pans fit flat, water stays in the basin, and daily cleanup takes half the time. The actual plumbing swap usually takes less than half a day once your fixtures are on site.
The best time to buy hardware is during major holiday home improvement sales like Labor Day, Black Friday, or Memorial Day. Before you buy, call two or three local trades to get quotes on labor so you aren't surprised by the installation bill.
Remember that a 0% interest window is a fixed deadline, not free money. If you still carry a balance after the 18 months end, high variable interest rates kick in on whatever is left.