When you first start to respec you get 2 weeks to do it, so that's 28 plus one more when the 2 weeks are up which you can save to use later.
You don't have to respec every 12h, you can just wait the 2 weeks.
I beleive that they have changed it so now you will get a masters badge even if you have not used your token respec. (That's the last one you can save.)
Or it will be changed next publish, not sure on that one.