But they aren't ready to produce the cheaper model, are they? What is the advantage to them announcing it many months before the start of production? I know there are people who would hold off on purchasing the Model 3 and Y (a stretch for them) if they thought the compact model was on the way "soon". I guess it would also make people who would only consider the compact model wait instead of buying a car from another manufacturer, though.
Exactly this.
Tesla started at the upper end of the market, and is working their way down. Many people make the "Tesla stretch." Many people went from a Prius to a Model S back in the day...if they had believed a Model 3 would have been available in 6 months or a year, many would have waited....and then Tesla wouldn't have had the Model S profits and investments to develop the Model 3.
The other car companies already have all their models across many market segments.
Nobody who really wants a Corolla is going to pay more to buy a Camry instead. But, Tesla actually benefits when people who really want a Model 2 decide to buy the Model 3 because they don't think they can wait for the Model 2 to be in mass production.
I think a lot of wealthier folks also assume people buy the maximum car they can "afford." There are, of course, plenty of people who do that...and also plenty of people who buy more than they can afford. But there are plenty of folks who decide more rationally, and buy the least expensive car that might meet their needs/wants. Those needs/wants don't have to all be financial and logical...there can be brand preference, preference for environmental friendliness, etc. If part of that need/want includes EV, then they probably turn to Tesla...and for many of those folks it would be difficult to justify a 3 or Y if they knew Tesla would have a car for $10K-$20K cheaper before too long.