Bloom booster doesn't boost anything. Ray has talked about this quite a bit. I don't think that watering has anything to do with timing the blooming either... mine are watered through the winter and bloom very well, pretty much every year. They do get a lot colder than they do at your house... nights down to 40 deg F (4 deg C) are petty common and occasionally lower. Pretty much all the speciosums grown along the California coast (and there are LOTS of them because they do so well) get the same weather pattern, might be a factor in all of them blooming about the same time plus or minus a few weeks.
I don't think there's anything that you can do to "make it bloom" faster. It'll do what it will do. (I have tried a "bloom dance" to encourage plants for shows
... doesn't work. But in general, one should not put calendars anywhere near the growing area
... they so often perversely bloom and finish just before a show or meeting, or open up the week after. )
Seriously, if they do bloom better after a rainy winter, to me that's a clue that "drying out" is not beneficial. Mine bloom quite well every year, and I do water Dendrobiums in winter - "rain" comes out a hose when Mother Nature doesn't cooperate which is most of the time.