You can see the code here, according to this there is no specific block it will start, they will start it at the given time. Also one hour earlier is additional presale for those who decided to bought for 2,5 USD instead of 3,6 USD from Bitcoinsuisse and then normal ICO starts
https://etherscan.io/address/0xbbc79794599b19274850492394004087cbf89710#code