Theraputic doses of gabapentin are upwards of 3000 mg, so building your self up to that level will take some time. Most people are used to the drug by the time they titrate up to that dose.
With that being said, i am currently on 1800 mg a day, along with other meds, and I'd like to say it helps. I have gained weight and I know it's from neurontin because every few months I'll stop for a couple weeks and loose some water weight I accumulate. That is the only side effect and I can live with that.