Until the Kickstarter starts, which is planned for November. At which point you can redeem the coupon and back the Kickstarter and get it at a “special price” which is estimated to be $379 (might change up or down). Presumably this is lower than the Kickstarter price itself without the reservation coupon. A bit of a convoluted system, but you can get your $20 back anytime, and it automatically refunds if you don’t back the Kickstarter or the Kickstarter never launches, so that’s cool.