You require to hold your BitConnect Coin minimum for 15 days to start earning Staking interest. You will see PoS minting Block in your wallet anytime after 15 days, the number of block you earn are based upon the number of coins you hold in wallet software.

If your staking amount is low then it takes more times to receive your interest block.
It can take up to 2 months even if your staking amount is low and staking difficulty is high.

No it is not necessary to turn on your system. The BCC staking reward cycle is 15 days, so you can open wallet after 15 days of last received interest block.when you open your Wallet You have to wait until wallet synchronize and your internet connection must be activate while you wallet synchronize.you will receive your BCC after your wallet fully synchronize.

Remember to take backup of your wallet file to restore BitConnect coin if your system crashes. Know more about to take backup and restore of wallet.dat file.For more info about staking visit here:https://bitconnectcoin.co/guide/8/How-To-Stake-BitConnect-Coin-and-Earn-Interest-on-your-BitConnect-Coin-holding