Bought my first keyboard! Looking for advice

learn some early Elton John and a bit of Honky Dory by Bowie,

As many as you can!
I would suggest you learn how to read music because that can help a lot in learning new techniques and appreciating/absorbing other pieces of music.

I was going to share my experience with keyboards, but in reading the post it wouldn't constitute advice as far as where you are looking to go with it.  

But here it is for what it's worth.

I never had any formal lessons.  When I was growing up, one set of grandparents had a functional electric organ and another a disfunctional old organ.  I just messed around with them when visiting.  Somehow or the other, I forget how, my Mom wound up with a cheap toy organ that I fooled around with a little in my teens.  I got my first synth when I was in college.  I went the book route to try to learn to read music.  One of the books was called The Adult Piano Course.  One of the first lessons was the opening bars to Frere Jacues.  I tried it out and played the next few bars off the top of my head.  I got a book of Debussy piano music.  From the little book learning I had indulged in I was able to make it through a few opening bars of a couple of his simpler piano pieces. He's done a couple of really simple yet beautiful solo piano pieces.  But in the end since I wasn't out to make a living off music I quit the book learning and just went with improvising.  When I'm in an inspired mood I can create some interesting stuff.   I've never actually put a formal song together that I could recreate.

Congrats!

As to how many hours a day do you practice, that would depend: Do you plan on learning how to read music (if you don't know already), or do you not want to read music?

If the latter (because although I can interpret sheet music, I cannot sight read and play it at the drop of a hat), then what I recommend is learning chords, scales, and progressions while simultaneously learning very elementary pieces of music- you can build from there.

If you want to be capable in less time, then it's probably best to get a teacher.