Thanks for the replies! I ended up snorting about 500mg over 8 hours which is probably a lot and I didn't remember much. I'm not sure whether I like it, it gave me very strange sensations around my body. I've still got 1500mg left so I'll leave it for a few days to keep my tolerance low
I hope you are aware that high doses of ketamine ( >1 gram per day) are damaging to the bladder and eventually the kidneys, causing a condition called "ketamine cystitis", also known colloquially as "K bladder".
If you don't even have a tolerance and you're already going through half a gram in a single night, you might end up having to have your bladder surgically removed in just a few years.