For the first 20,000 blocks, the issuance is limited by the "slow start" algo.

Each block the $ZEC issuance increases. 

At block 100, it was (100 / 20,000) * 12.5 $ZEC  = 0.0625 $ZEC.   With the target of 576 blocks/day, that means 36 $ZEC / day rate at block 100.

Blocks are targeted to come at the rate of one every 2.5 minutes.   (12.5 $ZEC every 2.5 minutes is the same as 50 $ZEC every 10 minutes, the same rat that Bitcoin started out with.)

At the current block, ~660 it is (660 / 20,000) * 12.5 = 0.4125 $ZEC per block.    With the target of 576 blocks/day, that means 237.6 $ZEC / day rate at block 660.

At Polo price of 19 BTC/ZEC, that's issuance at the rate of about $3M USD per day.  20% of that to the founders, 80% to the miners.

It's been just 8 hours since launch, and ZCash is already well into issuance of "day 2"'s coins.

This slow start is slow, sure.  But not anywhere near as slow as the "target" chart shows.   

Incidentally, at this moment, with 850,000 Sol/S ( https://explorer.zcha.in/ ) at this very moment in time, and have a $200 AMD 470 GPU ... you're getting ~20 Sol/S on it, worth about $70/day.