Every time you get interest.
Assume we have 1000 btcd.
1. You transfer the amount to your wallet and dont open it for 1 year. Then you open it and stake, you will get 50 btcd.
2. You transfer the amount and stake after 1 month. You will get (1000*0.05)/12 ~=4,167 btcd. Now you have a baseamount of 1004.167 btcd which you earn interest on.
So 2nd month: (1004.167*0.05)/12=4,182 and so on.
Maximizing this means staking 24/7.
Besides interest you also get txfees of the block which also stake.
And you are securing and supporting our network with it.
Happy staking