You are buying this desk so your lower back stops hurting and you actually want to sit at your computer. A solid wood top lasts decades, which means you pay once and never shop for a desk again. Look for dual motors and a frame with a solid steel lift mechanism so the top doesn't wobble when you type.
August is the best time to buy because office gear goes on deep discount for back-to-school promotions. If you want to save even more, check if the brand drops a new leg controller version; last year's frame is usually identical minus a minor app feature, but costs a lot less.
The 0% intro window is a deadline, not free money, so treat that 18-month mark as a hard stop. If you still have a balance left when the clock runs out, the regular interest rate kicks in on the whole original amount, which wipes out your sale savings.