I don't do propagation from seed, but from what I've read Phals can go from seed to bloom in about 2 years, maybe even less if you're really lucky; and Masdevallias can be pretty quick, too. On the other end of the spectrum, some Phrags are notoriously slow-maturing, and many Vanda-alliance species will make you envy Methuselah pretty bad.
Several twig orchids have been known to bloom while still in flask. If I remember correctly I think one of the words used in one of the articles was "precocious".
Orchids will not bloom in a seed flask because they are too young but they are able to bloom in a mericlone flask if the plant material has been taken from a mature plant.