ThAts a pretty high dose at first but the dose can easily climb up to 1800+ mgs a day some people even 3000-5000 but daily usage for long period of time is dangerous as shit.
I have 600s and if I wanted to get High right now I would take 1200-1500 mgs probably.
It's best to spread it every hour with some food or fats and take 300-600 mgs every hour rather than 1200 at once but everyone is different in how they want they High to feel . Some want to take it and get a "rush" but really no matter how much you take you won't get a "high" that people think of, at a certain point you get sleepy as fuck and it just lingers through out the day so it's not a drug to chase a high with.
You might wake up and get diarrhea sometimes, at least I did, from gabapentin so if u notice farts and bowel movements that are new it's probably that. Also a dry mouth time to time but nothing major, maybe grogginess the next morning that lasts and u feel off
Good luck