You want to start off each of your seeds in its own individual space, and then as they grow/fill out the container with roots you move each plant into its own larger container.
I suggest something like this to start your seedlings:
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I like to keep my RH around 70-90% inside the dome until they pop through the soil and then I remove the humidity dome. Once the dome comes off a fan comes on and never turns off. After that you can decide what size of pot you want to move into after your plants are a decent size and grown some leaves. As far as lights goes, check the deals thread. Keep in mind that vegging a weed plant and flowering a weed plant are 2 vastly different ball games.
EDIT: I start my seeds off in a 3.5" pot under a humidity dome, once leaves pop I remove the dome, transplant into a 1.2L pot after 1-2 weeks, and then straight into a 5gallon pot.