I'd think it would progress slowly, if that's the problem, but temperature will have a big effect. On an Acura I had, there was a small crack on the passenger side from a stone that did nothing for months. Then there were a few hot sunny days and it spread rapidly.

Online prices for the glass are in the $250 ballpark. You can do DIY glass replacement, but I'd probably look at paying for new with a good seal. That may be your root cause: moisture getting behind the seal, then wicking into the glass.