When you find the tractor you want at fair price. This will vary with demand and availability. It can vary with the model and not just the brand. If you chase the lowest price possible, and always wonder if you could not have done better and often you will miss a reasonable deal. Decide on what you want, try to have a couple of options as to brand and talk with at least a couple of dealers with those brands. I would begin with dealer nearest to you and then to another who is still reasonably near you. Watch web sites for some others but watch the dealer's web site not one of the big search engines for they often run a week or two behind the dealer's site so any good deals are normally gone.