How do u guys CS as Ahri ?

I dont know but for me it usually go like this i have arround 70-80 CS at Minute 10 arround 140-170 CS at Minute 20 and then I kinda give up with farming since the Teamfights are starting etc. arround 200 at Minute 30 and then i just keep decreasing my CS per Minute rate. I just wanted to know how other Ahri players farm and if they think farming as Ahri is easy. I have 250 k Points on Ahri and I still think i could improve alot in farming and the most of the other Ahri players i see in Montages or in my Elo ( Low Plat ) seem to struggle to farm properly aswell, does anyone here has any advices for me ?