Japan's JT-60 Tokamak Sets New Plasma Record
It isn't a question of how long. It is more a question of dollars.
It is often said that 20 years ago, the physics community estimated that they could have reactors working in 20 years. People usually ignore that this was only the first half of the estimate -- the other half was the level of funding needed to achieve the result. Needless to say, they received a small (and still shrinking) fraction of the funding they said was necessary, and the result is unsurprising.
Everyone laments the expense of large scale research in creating new basic technology. Bare in mind, however, that the production cost of the movie Spiderman 2 was a bit larger than the budget for the whole US fusion program the year it was released.