I tried the url you have in your docs
https://bittrex.com/Api/v2.0/pub/market/GetTicks?marketName=BTC-CVC&tickInterval=thirtyMin&_=1500915289433
1500915289433 stands for 2017-07-24T16:54:49.4330000Z however the result first item is 2017-11-01T09:00:00. Do I miss something?