Sterns marketing works well when u have a very limited market worldwide of people who follow pinball.
The buy now or miss out marketing hype really only applies to LE buyers who dont want to miss out. But I would never buy a BNIB machine from anyone ever until I have played it.
I only ordered a AC/DC Pro and a X Men Pro after playing them. The answer is to try before you buy.

Look at the marketing of movies these days. Marketed hard for 4 weeks before release. Marketed for a month after release, and then the movie finishs at the theatres usually within 4 to 6 weeks maximum. Marketing stops 100 %.  People lose interest very quickly on anything these days and impulse buys probably account for the majority of any luxury item sales.

Q - How early is too early for a Stern release to start advertising a brand new title ? ............  good question/hard to answer unless you are Gary Stern who would have a proven ? formula by now ? will have to look at Sterns past media dates to get a answer...