A utility trailer changes how you handle landscaping, debris, and hauling. You will save on dump fees and delivery costs, but remember you have to store it somewhere and keep the tires aired up.
Prices usually hit a low point in mid-winter when dealers are trying to clear out inventory. You can often get a better deal by walking onto the lot on a slow, cold Tuesday in February than you ever will in the spring.
This 18-month window is a deadline, not free money. If you have a balance left on the card when that time is up, you will be hit with interest on whatever remains, which can get expensive quickly.