That is exactly right. Keep doing what you’re doing. FYI distilled water is great when they’re little too because the liquid adopts the soil PH immediately.
They won’t need any nutrients; better to let them tell you when they need something, if anything.
There may be a bit of stretch happening; you may want to bring the light down a bit. I don’t know what that is on your leaves but I would try to avoid getting anything on them at this stage. High humidity is still good but you can start hardening them with a small fan playing on them for a couple of hours each day.
When you buy a meter avoid getting one of the 3 in 1 meters: they are worthless.
https://www.amazon.com/Apera-Instruments-AI209-Waterproof-Accuracy/dp/B078NPH1W3?tag=greenrel-20
This is the one I recommend.