Hi Rosie. Congratulations on your new baby!
Oncidiums prefer cooler temps, minimum winter temp 50* F and up to 65* in the summer. During the main
growing season, water freely, but in the winter, only water enough to prevent shriveling of the leaves. I pot mine in a finer grade bark/charcoal medium with a little moss mixed in, since they like more moisture than most. Speaking of moisture, they like higher humidity in the air than Phale's also, so keep the spritzer handy. I have only gotten mine to rebloom once so far in two years, so I can't help you much with tips on reblooming. The one time I got it to rebloom was from ignoring it, and stressing it out a bit from lack of water. Risky, there has to be a better way than that, I wouldn't recommend it.