On thing to note, though, with the Model X example is that the actual ramp-up means the Model X was delayed more like 2.5 years. Volume deliveries did not really begin until late H1 or by H2/2016. They were still delivering international Signature orders in Q3-Q4/2016. In Electrek parlance, Model X was a bit of a California compliance car for its two, three first quarters...
Certainly if e.g. Bolt EV is available widely by mid-2017, it is possibly means - even with a Model 3 reservation and a model release in late 2017 - that actual Bolt EV availability will still be over a year sooner than a Model 3 for many (most?) buyers. Availability of Model 3 in late 2017 might be similar to what Bolt EV availability was in late 2016.
Maybe Tesla will surprise us, but past precedent suggests at least some caution. Both Model S and Model X ramped up terribly, terribly slow. Model 3 can be expected to ramp-up faster due to a simple design, but even that IMO is not absolutely certain, and even if it ramps up faster, the higher demand at the lower price point might result people waiting for a long time...
We shall see. People were very optimistic Tesla had learned things by the Model X release. Alas, not. Maybe similar optimism will finally be rewarded by Model 3 release.