As for medium, I use medium size bark with perlite and leca. Water it once a week, or twice when temps are around low 80's (27ºC) at the growing site.

Good buy. It would be best to wait to repot when the flowers are done AND new roots are beginning. A fine or medium bark should do it, depending upon pot size. Those wiser than I may have other ideas.
Good luck!

It should be put into a larger pot for sure, that will allow the new leads to establish in media. I don't generally tear the roots apart. Small to medium bark. Fast draining. Oncidiums tend to like lots of water, and quick draining, fairly high to medium light (I would not have in in the center of a table, but either outside under shade or near a window).

Thanks for your input everyone! Very helpful. Optimist - it is currently in a window that gets plenty of light (but not direct sun). I only moved it to that table to get a good picture. I'm planning to repot as soon as the current blooms start to die off.
Thanks again!