One mind is gained through the bingo center. Every 30 minutes, it unlocks a new upgrade, and buying that upgrade will allow the bingo center to research a new upgrade, taking another 30 minutes. If you buy the upgrades as soon as they come out, it should take you appx. 2 hours and 30 minutes after buying the bingo center.
But, you MUST buy the upgrades, otherwise there will be no progress towards the next upgrade. So you have to purchase the Bingo center, wait 30 minutes, Specialized chocolate chips, wait 30 minutes, buy Designer cocoa beans, wait thirty minutes, buy Ritual rolling pins, wait 30 minutes, buy Underworld ovens, wait thirty minutes, then One mind will be available.