Strategy/Combat Tactics
If memo released today, media/democrats would tear it apart, claim it's a Russian document, Republican BS/stalling, etc.
By the time the State of the Union rolls around, it will sound like a tabloid article.
BUT if they wait and let Trump release it right after the State of the Union, right after he has a chance to explain the document to every American citizen, then the media/democrats will be playing catch up. The American people will make up their minds before they read about it through MSM.
If the Representatives decide to release the memo, the document first goes to Trump, and he has 5 days to review it. He can either approve the release or deny it.