By my reckoning, this only counts the forged total, not the total income earned. By the final chapter (7) and with all of the related upgrades, my forgers created $240 per hour, or $5,760 per day, with every previous day being a ramping up process to that number. At this rate, it would take just shy of 87 days to complete, but with the lower previous income expect the grand total to be somewhere around 160 days to forge.
This unlocked for me on Day 161 (and two hours).