[chc]

The Model 3 is supposed to already be in customers' garages in two years. The ramp-up better have happened by then or they'll be behind schedule.

As for why the ramp-up is a big concern now: There were several times more Model 3 reservations than Tesla projected, so they need to increase their production capacity in order to meet the demand. Getting ready to produce the cars is part of the ramp-up, and it's turned out to be a bigger task than they expected.

[ams6110]

Also the "reservations" are not contracts. If the Model 3 is significantly delayed, some number of those will not follow through with a purchase. Especially if there are other competing options on the market by then, which there almost certainly will be.