1) Seals are broken, web starts dissipating (or the DO starts unknotting or whatever). This leads to the DO's influence growing greater day by day, leading the world down a steadily darkening path. At last, he breaks free, and does battle with Rand. This seems to me like the most standard fantasy progression, allowing for the most change and drama.

2) Seals are whole, ripples are something else. There are only a few seals left, so things can't get a lot worse, exactly. One day the seals are broken (in one way or another) and the DO simply bursts free at some random time. Perhaps a time of Rand's choosing, if he breaks the seals. Obviously this would also work, but it seems less dramatic, to me. You don't have the pain and suffering of the DO's touch on the world to build tension before the battle. Rand just gathers his forces and says alright, let's do it.

Meh. Number one seems more likely, but who knows.