How the PoS is working.
When you get some GrainCoins in your wallet by any means (transfer, PoW minting, the output of the previous PoS mined block) the count of coin age starts.
When a single input get 10 days old it become eligible for searching the PoS blocks. It's weight grows day-to day until it get 30 days old, then the weight remains constant until that particular input is not spent. The more weight an input has the more probability that this input generates a PoS block. When the PoS block is found using some input then a few things happens:
1) a new coinstake transaction is created;
2) if the the block that contains the original transaction is younger than 30 days, then the coinstake transaction get two outputs, i.e. the input value is split in two parts. If the block is older than 30 days, then the split does not happen;
3) if split happened and the selected input value is less than one third of current PoW block reward then extra eligible inputs are added to this transaction until the total exceeds one third of current PoW block reward;
4) then the coinstake reward is calculated based on cumulative coinage of all used inputs expressed in cents per seconds;
5) then a PoS block is created using this coinstake transaction and submitted to the network.
All used inputs are spent in the step 5. The new output(s) start their own life with zero coin age.
If the block get orphaned due to any reason, then the transaction had no place and thus the coin age of used inputs remains intact.
So, basically you need not to run your wallet 24/7 if you have no many inputs. However, you can't predict when exactly all your inputs would create a PoS blocks. The only thing you could be sure is that the wallet will not generate any PoS blocks while any of your inputs are younger than 10 days.
Yeah coin age would not be an issue for all the coins are well over 10 days lol.
What I will do then is move the wallet to a miner which of course runs 24/7 and keep the wallet open. Outside of the PoS, it also adds connection to the network.
Glad to see you are working on the coin. I dont have a huge stake like many do, but heck I might even toss in a cpu or 2 at it to keep it moving.