I created a black and white spring treasury!
Sometimes it does take some luck to get a treasury, but here are some pointers...
Craftopolis.com has a treasury clock that counts down to when the treasury will open. It can give you an estimate of the time to check, but it is always good to go to the treasury ahead of time and check. Sometimes people close their treasuries early, and then the treasury opens up sooner than predicted.
Have your title ready ahead of time. Type it out and copy it. I don't know if you've seen what happens when the treasury opens... but a little space pops open at the bottom of the screen for your title. You have just a few seconds to type it before it goes away and you miss the chance. So... if you have it copied, you can just paste it, and hit the create button.
And, most importantly, do not refresh your screen when you are waiting for the treasury to open. That was my mistake my first few times trying. Etsy automatically updates the treasury page. As the time runs out for each treasury, they go away. When the 333rd one goes away, you'll see a little message pop up automatically at the bottom of the page. That's where you paste your title, and get your treasury.