I puked up my last bottle of Robocough and now I'm realizing I never quite figured out how to keep DXM down

There was a while when I'd space out the bottle into quarters every 5 minutes, but the onset of the trip would take waaaay too long. I want to be able to get hit with the trip as soon as possible but after that last puke it's clear that the whole bottle at once is a huge mistake. Is that ALWAYS a mistake? Is there a best way to consume DXM to get the whole trip as quickly as possible?