How wet should my soil be at this stage? The seedl...

At this stage, just focus on the basics as she will grow regardless with good light, water and light air ventilation. Make sure your night temperatures don't drop too low as it can stunt or even kill your plant so early on. Try keeping your night temp above 18 Degrees C. Secondly, don't over water.. a bit a time is better than too much all at once if you're not sure. As you can add but can't take away. Overwatering is another problem that will stunt your plants growth. So less is more. No nutrients is needed at all at this stage, just water pH'd to around 6.5 as its what I use, and proven to be best range in soil. That soil mix has enough in it to last you 3-4 weeks, so no nutrients is needed. Check out my diaries if you need any guidance or happy to help via message. Lastly, higher humidity at around 50-65% will help her growth through the seedling and veg stage. If you're out doors anything that can give you a greenhouse effect will help. Not only with humidity but raising the temperatures! Hope this helps