Totally possible I got seeds from cali 3 days ago mailed to a nearby state. find a friend in cali. ask them for seeds to b mailed in a crush proof envelope which can b bought at many local stores, walgreens, cvs, post office. lol
i usually start with flourecent then switch to hps after my plants like 5-6 inches. but yea 20in. is fine make sure the fans breeze is strong enough to get the stems movin a bit to make thm thicker.