As I understand it, it has to have the updated blockchain and be running by the stake date.
If you leave it running you help the network, and don't have to worry about your stake.
Do you need to have your client constantly "on" to receive the state?
Or could you set up yourself to receive stakes,not use the client for several months,and then return to find you have loads of stakes?
The client must be open and synced in order for the PoS blocks to attempt generation...
you can leave the client closed and then open and sync it just before your coindate reaches maturity for stake, and then it will be eligible to do so... but leaving it offline will NEVER generate stake ever. The point of stake is to solidify the network from 51% attacks by keeping wallets online and synced constantly even if you aren't solo mining.