we started wiping Calvin's teeth as soon as he got them! (at just past 6 months.) we used gauze at first as two little nubs didnt seem enough to use a toothbrush on. and now, we've been brushing his teeth twice daily for a while now. (alternating berry and mint toothpaste so we doesnt just like the fruity one.)
most things i've read say you should brush as soon as the teeth as there as babies teeth can decay just like ours.
now getting Calvin to try to brush his own teeth without gnawing the toothbrush... well, we're working on that!
if Ethan sees you brushing your teething, maybe he won't be intimidated by it. but i would definitely get a soft baby brush and start getting him used to it without toothpaste at first
its often not that bad!! C will (on MOST days/nights) let us hold him and brush his gnashers (tops and bottoms) with no problem!
good luck!!:)