Don't you just hate it when you buy something new, only for it to be obsolete a week later? In the world of tech, this is bound to happen. New products are released, sometimes without warning, all the time. However, you can protect yourself somewhat by keeping in mind when new products are due to arrive on the market. Maybe it's worth waiting a week or two to see what the new model brings.
Worst case, you know for sure you're not interested in the new model. Best case, you get the new model instead. Perhaps the company will discount the older model and you'll save some money. So that's, um, also a best case?
Below are some general timelines that should help you get a better idea of what gets released when, and when you can commonly expect to get discounts. Keep in mind that it's possible these dates will change, and sales can happen randomly throughout the year.
Some general guidelines
For the vast majority of new products, new models are announced at the Consumer Electronics Show at the beginning of January. CNET does wall-to-wall coverage all week, so you're not going to miss anything. Keep in mind, though, pretty much none of those products are actually available in January. For the most part it takes a few months for the products to ship. Which is to say, if you read about a new TV in January, you won't be able to buy it until the spring or summer.
However, due to a combination of both CES and the Super Bowl, January is a great time to find big discounts on the previous year's TVs. Sometimes prices are even better than what you'd find during the holidays.
Speaking of holidays, this is definitely a good time to find deals. Every company wants/needs to make massive sales in the fourth quarter, and some will do whatever they can to get those numbers up. "We're losing money on every one, but we'll make it up in volume," as the saying goes. This is especially true of LG's OLEDs, which often drop by incredible amounts as winter approaches.
There are some exceptions. Apple, of course, beats to its own drum. It usually announces new laptops in the spring, and phones in the autumn. It also has a strong history of having its products available right as they're announced while almost never discounting its gear. Also, for the most part, it alternates years with big and little changes. So last year was the iPhone X, this year will be the iPhone X "S" or something. Next year will be a more radically different "11" (or something, maybe the "XI" or "Elevensies").
Samsung and Google are generally following Apple's "not in January" approach with their smartphones, but at different times of the year. Samsung historically announces at the Mobile World Congress in February. Google does it at its own event in October. In both cases the phones are available shortly thereafter.
Other products are more random. If they're not announced at CES, or the other big trade show IFA in September (less common), they might get announced any time during the year. Because it's more random, it's less worth worrying about. The big companies tend to follow a pretty predictable pattern. A pattern you can see here:
Best time for tech deals
|December/January||TVs||Holidays, January for previous year's models|
||Media Streamers||Holidays, Random|