i dont understand timebank???
First of all read this carefully:
https://docs.google.com/document/d/1RLcjSXWuU9vBJzzqLEXVACSCdn8zXKTTJRN_LfoCjNY
do i keep my cinni in exchange or what do i do with it?
That is up to you, you can keep in exchange or send to your wallet, in both cases you will get 10 Timebanks for 1 Cinni.
I recommend you send to your wallet and start staking to get more Cinni.
Best Regards