Genesis block was still under construction the next day according to posts in NXT thread. Indeterminate when it was started, but if the coin that went in while I was waiting for an answer was included, then mine could have been as well.
Again, the math: presale price = 21 BTC/1,000,000,000 NXT = 0.000000021
price when first offered in NXT sale thread = 1,000,000 NXT/BTC = .000001
.000001/.000000021 = 47.62 = 4762% increase in price
If you bought right after the genesis block at 0.000001, it'd be worth 0.000085/0.000001 = 85 = 8500% increase in price.
So the initial stakeholders actually made most of their gains
after the fundraiser... which meant that NXT was already released and anyone could buy in with less risk.