I don't grow this plant so have no first hand insight for you. I've beem searching the forum for information, but so far there is no mention about when these start to wake up.
Bud gives some pretty detailed information about culture here, and there is good information in the rest of the thread:
Peristeria elata (Dove Orchid)
In another old thread someone noticed a new growth right around this time of year:
Peristeria elata new growth?. Keep in mind that this likely varies, so growths can also occur several weeks before or after this!
I hope she is aware that this is NOT an easy orchid to flower.