In my case, I didn't find that it worked much at all. It was supposed to reduce my anxiety. It didn't. From what I've read, there isn't a lot of evidence that gabapentin can do much for psychiatric problems. This drug is an anticonvulsant. It has proven to be useful in reducing certain types of seizures. It can also help you to fall asleep.
Somewhere along the line, psychiatrists came up with the bright idea that a drug which reduces pathologic seizure activity might very well confer other benefits on the brain. I believe some of that was wishful thinking. I was put on a few different anticonvulsive drugs. None of them did squat for my depression or anxiety. It's easy to find articles on the Internet that say using these drugs for psych problems has taken off like a fad that is not proving all that effective. I have seen multiple articles claiming gabapentin does reduce social anxiety. For that, they claim there is some real evidence. I don't know how long that takes to kick in.
It definitely stimulates your appetite. That effect kicked in right away for me. I was already carrying some extra pounds, so I was not happy to find myself eating more.
I think benzodiazepines work quickly to reduce psychological distress . . . if you take a big enough dose. That's why benzodiazepines have high street value. They do provide a quick fix, but that can wear off over the long term. Then you find yourself addicted and taking them just to stave off withdrawal. That happened to me with Librium.
For depression with anxiety, the best drug I ever encountered was amitriptyline. They say it takes weeks to kick in. Not in my experience. Anytime I went back on it, after being off it a few months, I felt much improved in 3 or 4 days.