It's trival to create a PoW system with that creates coins according to whatever schedule you want.
the 'schedule' is based on number blocks, not a timestamp though , right?
If you like. It is in Bitcoin.
From the Wiki. Although based upon the number of blocks, it is effectively a calendar schedule too, because the system attempts to average 10 minutes per block.
Block creation fee
The block creation fee changes at every 210000 blocks. The block creation fee is a function of block height on the chain (genesis=0), and is calculated using 64 bit integer operations (in satoshis) as:
(50 * 100000000) >> (height 210000)
The block creation fee started with 50 BTC, has fallen to 25 BTC at block 210000, will fall to 12.5 BTC at block 420000, and finally down to 0 satoshi with block 6930000. The block creation fee of all coinbase transactions will sum up to 2099999997690000 satoshis, practically 21million BTC.