Do you have $1,500 and a penchant for punctuality? Then you're halfway to becoming a Google Glass explorer.

Google announced Thursday that it's opening up its Glass beta-testing program to all adults in the United States, starting on Tax Day -- April 15.  Anyone fitting those qualifications can sign up starting at 9 a.m. ET. But you'll have to move fast.

Google hasn't said when it will stop the open sign-up period but warned in an official G+ post that there aren't a lot of spaces to spare. "The number of spots available is limited, so mark your calendar if you want to get in," the company said.

You'll still have to pay the full price of $1,500, plus tax, for the headset if you get into the program. But you will be able to pick your color or favorite prescription frame for your Glass unit.

To sign up, be ready to hit the Google Glass Explorer Program Web site right when the sign-up starts, and have your name, e-mail address, phone number and country of residence set to type. Also, be prepared to explain why you want Glass -- to develop for it or use it for research or for business.

Google has been steadily expanding its Explorers program since its launch in 2013, but sightings of the headset -- outside of the Bay Area, at least -- are still fairly rare apart from developers conferences.  In fact, the device made what's believed to be its congressional hearing debut on Wednesday, on the face of topcoder's Narinder Singh.

Yet while Google has at work getting Glass onto the faces of professional athletes, surgeons, firefighters and the fashionable-yet-nearsighted, the company still hasn't shared any information on when consumers can expect a commercial release.

In other words, if you really, really want to get your hands on Glass, next Tuesday is probably your best bet for now.