Hard to say exactly, actually. You would think the onset is due to rapid administration, which it is... So you might expect the same thing with any psychedelic administered rapidly.
But this is not the case, the rapid onset of psychedelic effect does not always correlate with rapid administration. Often what happens is the physiological effects hit immediately, BP rise, HR rise, but they psychedelic effects themselves still take some time to build, 15-20 minutes usually. Some that come to mind are EPT and DET. LSD has been administered IV and it behaves the same. The 4-HO analogues follow suit, my guess is that psilocin does the same...
In other cases, the psychedelic effects hit hard and fast, like with DMT, or 5-meo-DMT. Synthetic ones like MPT and DPT (although this is a bit different) do too.
Although... Its not that black and white, if you eat enough psilocin, it hits like a ton of bricks.
And if you eat enough DMT orally, you can have the breakthrough experience, you will at some point reach the same place...