Maybe you should try to see on the bgold website, what exchanges already support them. Last time I checked, those two weren't there yet. Not saying they wont list it, but right now, we don't know if they will.
be careful where you check! there are a lot of fake websites out there claiming to be bitcoin gold's website. i saw one the other day which was asking for ICO funds to be paid to a certain address!
the real one is called BTCGPU.org and they just made the website today. and it has no mention of exchanges to trade this.
it is funny how their website says "transparency" and yet there is no mention of the premine!