Don't worry yet, two weeks isn't too long. If it gets to four then maybe start to panic a bit ha ha. To be honest 16 degrees isn't really warm enough. They'll still work, but they will take longer to get going. Aim for more like 20-22 degrees. I'd also cover them to increase the heat and keep the soil moisture in, and pop them in the airing cupboard perhaps. They don't need any light while they are seeds. Only once they have germinated and broken the surface do they need the light.

Another big mistake that a lot of people make is planing them too deep. They really don't have much energy to get to the surface, so just literally cover them with a thin film of soil. Plant them a couple of centimeters down and you may find they germinate but never make it to the surface.