You will have to measure the humidity when you have larger plants in the room. By the time they are a foot tall you will probably have a much different humidity reading. 90-100% is best for small seedlings, 70-80% for vegging and under 40% for late flowering. The most important one is to keep humidity down during the end of flowering. If you have a different humidity level for vegging they will still grow. High humidity for the first week or two stops the seedlings from drying out, which can happen easily if the lights are close to the canopy, and it will stunt growth for a few days/weeks. A plastic dome of some sort is good for babies. Higher temps usually lower relative humidity and vise versa.

And good luck