Hi man!
The wonder of changa is that if you load it into a pipe or a bong there is no need to clear the entire bowl. Quite simply load the bowl and proceed to toke how ever much you deem yourself to be comfortable with.
Be sure to take it slow to begin with. I would suggest loading the bowl, but consciously proceeding with a small toke that I am certain will not floor me. Observe the effects, sublimate the experience.
( I say load it fully so that if you want to go further there is that option, quite literally, on the table. -- also don't hold the flame to the changa. Just get it burning.)
From there the choice is yours. One can hit the gas, or slam the brakes. This is in a sense the beauty of changa; the buildup of MAOI in your bloodstream means that each toke after the initial one will gain potency, not solely by measure of the actual size of
that toke, but by a compounding effect of MAOI's building in your bloodstream.
With that in mind, be weary, and understand the compounding effect of a session of changa: start slow, enjoy yourself, and gauge your willingness to dive deeper.
The metaphysical comfort--with which, I am suggesting even now, every true tragedy leaves us--that life is at the bottom of things, despite all the changes of appearances, indestructibly powerful and pleasurable--this comfort appears in incarnate clarity in the chorus of the satyrs, a chorus of natural beings who live ineradicably, as it were, behind all civilization and remain eternally the same, despite the changes of generations and of the history of nations.
--Nietzsche
Ontology has it backwards. “This ‘saying to the Other’ — this relationship with the Other as interlocutor, this relation with an existent — precedes all ontology; it is the ultimate relation in Being”
--Levinas