This is quite easy to do with a PowerShell build step using the following source code:

echo "##teamcity[setParameter name='env.BUILD_START_TIME' value='$([DateTime]::Now)']"

or (for UTC):

echo "##teamcity[setParameter name='env.BUILD_START_TIME' value='$([DateTime]::UtcNow)']"

This uses TeamCity's Service Message feature that allows you to interact with the build engine at runtime e.g. set build parameters.

You can then reference this build parameter from other places in TeamCity using the syntax %env.BUILD_START_TIME%

The advantage of this approach is you don't need to use a plugin. The disadvantage is you need to introduce a build step.

This is quite easy to do with a PowerShell build step (no plugin required) using the following source code:

echo "##teamcity[setParameter name='env.BUILD_START_TIME' value='$([DateTime]::Now)']"

or (for UTC):

echo "##teamcity[setParameter name='env.BUILD_START_TIME' value='$([DateTime]::UtcNow)']"

This uses TeamCity's Service Message feature that allows you to interact with the build engine at runtime e.g. set build parameters.

You can then reference this build parameter from other places in TeamCity using the syntax %env.BUILD_START_TIME%

The advantage of this approach is you don't need to use a plugin. The disadvantage is you need to introduce a build step.