I am frequently spawning Eclipse workspaces with Oomph setups and the first action I do when a new workspace is provisioned is to close Eclipse’s welcome page. So I wanted to suppress that for a current project setup. So I started searching where Eclipse stores the preference that disables the intro page. The location of that preference is within the workspace directory at

.metadata/.plugins/org.eclipse.core.runtime/.settings/org.eclipse.ui.prefs

The content of the preference file is

eclipse.preferences.version=1
showIntro=false

So to make Oomph create the preference file before the workspace is started the first time use a Resource Creation task and set the Target URL

${workspace.location|uri}/.metadata/.plugins/org.eclipse.core.runtime/.settings/org.eclipse.ui.prefs

Then put the above mentioned preference content as Content value.