First, are you taking extracted harmalas AND Caapi ("Ayahuasca"
? Or do you just mean extracted harmalas and some kind of DMT salt?
For DMT to be active orally, you have to take harmalas orally. Once orally inhibited, though, if you choose to smoke after, things can get very insane very quickly.
So, if this is your first time, I would recommend with getting familiar with each individually, and then combining judiciously. It's great to have a deep experience, but it's not so great to get unnecessarily sick and terrified, especially in unfamiliar waters.
Ideally, if the brew is held for about an hour, you should be fine. I've purged 10 minutes after drinking (I was chasing the tea with some mango and vomited all over my plate on the table...
) and still had a complete experience. I have seen others vomit early, though, and sometimes the experience aborts--but that could have been for a number of reasons.
I would not recommend trying to induce vomiting at any point. You may not vomit. You may not even feel nauseous! I vomit maybe 1/20 times. I know other people who vomit all night, every night they drink. In any case, the best thing to do is just surrender. Keep a bucket nearby if you need it, but just resign yourself to the experience, enjoy and learn all you can. Trying to induce vomiting feels like a mind > body approach, when, really, lots of the beauty of the experience is quieting the mind and learning to identify with the voice of the body.
Also, inducing vomiting is different than being forced to purge by the medicine. Once the medicine is active in your body, regardless of what is actually in your stomach, if you are meant to vomit, you will vomit, and nothing in the world can stop it.
Some things will come easy, some will be a test