Is the Minecraft aquatic update out yet for the Xbox 360? If not, when is the estimated time until it's realesed?

Since the XBox 360 version of Minecraft is NOT running on the Bedrock Engine, it has not been released at this time (of post)… But it's still coming for the XBox 360 & Playstation systems as it took some time for the update to hit the Java Edition.

The XBox 360 would likely update automatically when it gets released, assuming you have that enabled on your console.

Please be aware that the Update Aquatic is the Final "END OF LIFE" Update for the console versions (excluding the New 3DS & PS4) NOT running on the Bedrock Engine… So don't expect any other updates beyond this.