I count time from the moment I noticed a spike that is just starting to grow and to the moment buds are open, at least one bud.
Maybe it is different for different intergeneric hybrids.
I think several other factors may play some role in slowing or speeding the process: temperature, humidity, light. Having said all this, it can be different for your orchid.
I had been searching for a spike, looking in the leaf spaces, so I saw the spike when it was only about 12mm (half inch) long. Its now reached to the top of the foliage. So still some way to go yet.
Its grown outside under a verandah.