Here's a critical question for you: is the money for the full amount of the item coming in, or is this actually something you're going to need to put some effort into saving for?
If you're expecting the money to come in on X date, then put a follow-up on your calendar or in your tickler file that date, or just before, to remind you that the money is earmarked for this item.
But if you need to save for it? You've actually got a project on your hands called "Save money for thing."
For instance, my car potentially needs a new catalytic converter. I'm a living-on-a-shoestring grad student. An $800-1500 car repair is a little out of my budget. But I need to pass my inspection, so this is definitely a project to be done as soon as possible. Since I do my weekly review on Fridays, which is also payday, one of my steps in my WR is double-checking my finances, and tucking away what I can toward things I'm saving for. So I essentially have a recurring NA on this project of, "Put as much money aside from paycheck as possible for catalytic converter."
If you're not invested in doing this on the item, then it's probably a someday/maybe item and belongs on such a list.
I find that thinking about purchases as projects vs. someday/maybes this way is more useful than the typical personal finance "wants vs. needs" hierarchy. Either an item is something to be bought as soon as possible, and I need to move on saving for it, or it's not, in which case it belongs on the "if a big bag of money lands in my lap" kind of list. Sometimes "wants" end up on the projects list. Yeah, I didn't need a Blu-Ray player. But watching Netflix on my TV was a sufficiently attractive benefit that I found it worthwhile to make saving for a BR a priority, and I've had my BR since March.