At the beginning of your upkeep, The Prismatic Bridge triggers, revealing cards from the top of your library until it reveals Timestream Navigator and puts it onto the battlefield.
Pass the turn.
At the beginning of your next upkeep, The Prismatic Bridge triggers.
In response, activate Timestream Navigator by tapping it, paying ({2} magic symbol) ({U} magic symbol) ({U} magic symbol) , and putting it on the bottom of your library, taking an extra turn after this one.
Resolve The Prismatic Bridge's trigger, revealing cards from the top of your library until it reveals Timestream Navigator and puts it onto the battlefield.