Orchids are epiphytes which grows on tree branches in the wild.
For first week of mounting the orchid water it everyday until the orchid adapt to its new media. I am using tap water room temperature, not too hot or too cold, you can also use rain water if available. Just water the roots avoiding the leaves. I never use ice to water my orchids, they are tropical plant and wouldn't like the cold.
Do not move the orchid to a new location after mounting it to avoid transplant shock, for instance, if the orchid was placed in east facing window, the mounted orchid should be place back to the spot.
For the following week, water it twice a week especially in the summer.
Then water it weekly or sparingly in winter time. The twine can be removed when the roots anchor itself to the wood.