The good news is that when I stopped, my brain came back almost immediately, and in force. Basically as soon as I could tell that I hadn't recently smoked. A few days, tops.
What helped me to quit the most actually was buying some horrid weed from my guy that I still insisted on smoking. The stuff was low-grade enough that I was going through slow withdrawal even during the weeks when I was smoking it. And smoking it was no fun. I know for sure that my symptoms this time around pale in comparison to the times in the past when I briefly quit (for a drug test or whatever) after smoking that bubonic chronic (SFV OG, GSC and such).