"After the Ethereum Dev call yesterday it has been confirmed the release date for Byzantium will be at block 4,370,000 which should be mined on October 17th. They were originally aiming for block 4,350,000 which would have been October 9th however have given them self another week to ensure everything is tested. After the difficulty bomb that went off yesterday, we are going to land at about 29s block times between now and then. After October 17th, we should see our mining rewards improve by approximately 23% from what it is after this latest difficulty bomb adjustment.
" Byzantium will land on block 4,370,000 so we will have approximately 2,380,000 blocks before 3GB cards will no longer mine Ethereum. At 14.1s blocks, it will take ~388 days from October 17th 2017. This will put the end of life date for 3GB cards on Ethereum at November 9th 2018."