Tesla fans who wanted to be near the top of the waiting list for Tesla’s new Model 3 mass-market electric car camped outside of Tesla stores overnight in long lines. They were probably the smart ones.
As the reservation list soars—from 115,000 early Thursday night, to 135,000, to 180,000 Friday morning—the length of time that reservation holders will have to wait for a cars is growing fast. Tesla CEO Elon Musk tweeted shortly after 1 pm (est) on Friday that the list had now grown to 198,000.
The backlog is mostly a blessing for Tesla (TSLA), but it could also turn out to be a bit of a curse. Soon, new reservation holders may not get their cars for three or maybe even four years while also potentially missing out on a federal tax credit that expires after Tesla sells 200,000 cars.
Musk knows as much and tweeted: “Recommend ordering soon, as the wait time is growing rapidly. Definitely going to need to rethink production planning.”
According to analysts at Cairn Energy Research Advisors, Tesla, which will start shipping the Model 3 at the end of 2017, could ship 76,860 Model 3 cumulative cars by the end of 2018. That includes 12,200 shipped within the year of 2017, and 64,660 shipped within 2018.
In my mind those are pretty optimistic numbers, as Tesla predicted it would start shipping its Model X crossover SUV cars by the end of 2015, and then ended up shipping only about 250 Model X cars in 2015. And remember Tesla has only delivered a little over 100,000 cars in total over its lifetime.
While not all reservation holders will ultimately buy the Model 3, let’s say they do for argument’s sake. You’d need have a reservation number lower than 76,860—the predicted total to be shipped by the end of 2018—to get one before the end of that year. If only half of the Tesla Model 3 reservation holders convert into buyers, then you’d need to be in the first 153,720 reservation holders to get a car by the end of 2018.
Tesla doesn’t disclose its conversion numbers, and its hard to know what they may be. And the longer it takes to manufacture the cars, the conversion rate may drop. If there are unexpected delays, it drops even further.
Many of the current Model 3 reservation holders, particularly those who signed up online last night and this morning could get their cars in 2019, or three years from now. Cairn Energy Research Advisors predicts that Tesla will ship 212,646 Model 3 cars (that’s cumulative) by the end of 2019.
Again, say, if all of those reservation holders convert into buyers, you’d need to be on the reservation list under 212,646 to get a car in 2019. According to Musk’s latest tweet, there’s only 14,646 spots left to get a Model 3 in 2019 (assuming 100% conversion).
Get Data Sheet, Fortune’s technology newsletter.
And again if only half of Tesla’s reservation holders turn into buyers, you’d still have to be within the first 425,292 to get a car by 2019. That’s a little over double what the waiting list is now in just the first 24 hours. If reservation sign ups don’t slow, then the list could reach over 400,000 by the weekend or early next week.
By the end of 2020, Tesla’s Model 3 supply is predicted to increase and hit a total of 409,536 cumulative shipments, and 196,890 just within 2020. If you wait for many more days and weeks to get on the Model 3 reservation list, you could easily fall into this 2020 time frame.
In reality, though, Tesla hasn’t said exactly how it’s going to allocate the cars to people on the wait list. It has said customers in California might get preference (near Tesla’s headquarters) and also former owners of Model S and Model X cars might get preference. Will different features that customers eventually buy add or subtract from wait times? At this point, it’s too soon to know.
In addition to the lengthy wait times for the car, after Tesla sells 200,000 cars, it’s set to lose a $7,500 federal tax credit for its customers. So if you fail to get your car in 2018, the Model 3 is will likely be that much more expensive. Soon, any new reservation holders will be past that point.
Fore more on Tesla’s supply chain innovations read: A Lithium Gamble That Could Win Big for Tesla
Will Tesla change its Model 3 production plans, as Musk suggested to meet the demand? Well, it’s hard to say. The Fremont, Calif., factory can produce 500,000 cars annually, so it would be only have to grow its production within the current factory to hit those numbers. Tesla’s huge battery factory, under construction outside of Reno, known as the Gigafactory, may be the more difficult one to speed up because construction is already moving at a breakneck speed there.
Despite its ability to attract reservations and buzz, Tesla is already spending heavily to get to the point where it is today. It’s unclear how much more the company will be able to invest into increasing production beyond what it’s already publicly stated. It’s already raised billions of dollars to cover the ballooning costs.
A huge wait list is obviously great for Tesla, but the down side could also be some unhappy customers who grow tired of waiting and jump off the wait list. In that respect the reservation list could end up shrinking considerably.
At the same time, being one of the first Model 3 owners is an experience, similar to buying the first iPhone (though many times more expensive). Early adopter customers tend to be more willing to forgive wait times, or even delays, if it means they can be part of a movement. That’s exactly how the Tesla customers who were waiting in line overnight to get on the wait list felt. They were cheerily happy to be a part of the community and experience of being an early Model 3 owner—even if they weren’t one yet.