Ime Tryptamine is pretty quickly methylated to NMT, assuming one has enough B12/SAM. If you don't have enough B12/SAM then it can't be methylated and so then you can feel the Tryptamine for a longer period of time, though i can't remember how long it seemed to last, definitely a good few hours though since MAO-A is inhibited and so the Tryptamine can't be metabolized out while MAO-A is still inhibited, iirc it was about 7 hours in total that it lasted, while if one doesn't take the B6 with the Tryptophan it's around 7 hours in that i start feeling Tryptamine cerebrally/in the brain/prefrontal cortex-wise which by then only lasts a short while because the brain's MAO-A inhibition starts waning sometime after.
But yeah as far as the NMT/DMT portion goes though it seems typical for the usual duration of NMT/DMT, so orally about 4 to 5 hours, or shorter cerebrally.
I wish someone out there had some pure Tryptamine or pure NMT (since NMT is the immediate precursor to DMT), and try taking it orally with the Harmalas to see how it compares to this method of endogenous Tryptamine synthesis, i'm willing to bet it'd be pretty much the same.