I'm also guessing any plant with a substance that acts as a MAOI would probably potentiate the effects of lots of other substances. So my guess is that it may not have taken that long for at least one person (or maybe multiple people independently) to discover that this plant seemed to alter the effects of other plants.
Then at that point some adventurous people may have just started trying combining it with every other plant they knew about and every future one they discovered, including plants that they otherwise believed had no effect. They probably would've stumbled upon a lot of interesting combinations.
And if they determined it had a strange ability to seemingly "unlock" "dormant" plants and if they spread that knowledge, maybe some people were trying it with absolutely every non-poisonous plant out there. And since DMT-bearing plants are pretty common (as you mention), multiplied across a whole society it may not have taken very long at all. And it would take just one MAOI plant for them to get the idea that other plants might have this unlocking ability, and just one DMT-rich plant to discover other plants might have similar effects, so maybe they iterated through combinations of MAOIs and serotonergics until they found one they felt had a good balance of maximal power and minimal undesired side effects.
So the bottleneck might be the first instance of someone ever discovering any kind of MAOI plant (this vine or any other). After that barrier is passed, I suspect it might be almost inevitable that something like this particular combination would be found pretty quickly (just blindly speculating, but potentially within a generation or two?).
Then at that point some adventurous people may have just started trying combining it with every other plant they knew about and every future one they discovered, including plants that they otherwise believed had no effect. They probably would've stumbled upon a lot of interesting combinations.
And if they determined it had a strange ability to seemingly "unlock" "dormant" plants and if they spread that knowledge, maybe some people were trying it with absolutely every non-poisonous plant out there. And since DMT-bearing plants are pretty common (as you mention), multiplied across a whole society it may not have taken very long at all. And it would take just one MAOI plant for them to get the idea that other plants might have this unlocking ability, and just one DMT-rich plant to discover other plants might have similar effects, so maybe they iterated through combinations of MAOIs and serotonergics until they found one they felt had a good balance of maximal power and minimal undesired side effects.
So the bottleneck might be the first instance of someone ever discovering any kind of MAOI plant (this vine or any other). After that barrier is passed, I suspect it might be almost inevitable that something like this particular combination would be found pretty quickly (just blindly speculating, but potentially within a generation or two?).