I know Sanj is on the same boat as you, but he got new rims.
Nice ones too.
It'll take more than 5-6 months for the dirt tracks to settle, I went through it and it was over a year before it got really better. But yes, you'd have to clean them at least twice a week. If you don't want to go through that and can get the deposit back, wait till next year, and perhaps go 18"s too.
btw if you want some extra performance, you can pick up other 17"s that are way lighter for around the same price.