I can't remember if my lemon thyme usually greens up late-ish. Mine is in a huge plastic pot so it is pretty exposed to the weather and not warmed by any stone. No signs of green yet. But it is one of those plants whose dry, thin, fragile stems seems dead even when they are not. I do remember that much.

As a comparison, oregano seeds germinated 2-3 weeks ago, though they have progressed very little.