As in not ever.
Let's first understand the issue: it's that a minority is blocking there even being a vote on nominees the President of the United States wants to serve in his cabinet. The minority isn't voting "no," they're saying no one can vote.
This has never happened in the history of the country for Secretary of Defense. The Senate has never done this in 224 years. (They've only, done it twice for anyone, both minor nominees. Interior and Commerce. Not national security. In two centuries.) It doesn't mean they can't. Just that -- well, it's so monumentally stupid that it can only serve to backfire on you when you do it. After all --
1) The country just had an election, and by a solid majority said they wanted Barack Obama to be president. You have to assume, therefore, that the public wants him to choose the people he wants to help him lead it. After all, if the American public had wanted Republicans to lead the country, they'd have voted for Mitt Romney. But they chose Barack Obama. So, why minority Republicans think filibustering the cabinet nomination of the just-elected president is a Smart Thing is something between them and their personal God.
2) The cabinet position they're blocking is for Secretary of Defense. National security is considered a Quite Important Job to many people. Especially at a time when we're involved in overseas conflicts. So filibustering the nominee, Chuck Hagel, leaves that position in uncertain flux, and deeply politicizes it. You have to assume the public might see this as really quite an irresponsible thing to do.
3) Chuck Hagel is a Republican. His nomination shows that the president is trying to be bipartisan and get past political gridlock. Attempting to block Chuck Hagel only hammers the perception that it is Republicans -- and Republicans only -- who have no intention of working together and do what's best for the country.
4) If the the first filibuster of a Defense Secretary in U.S. history does cause the president's choice to withdraw, it would even be worse for the GOP. When Republicans forced Susan Rice to withdraw her nomination for Secretary of State -- a highly-qualified black woman -- it was disastrous message for a party having deeply-serious problems with minorities and women. The added reality of Republicans doing the same thing (yet again) with a nominee from the OPPOSITION PARTY will only remind people of Republicans' close-minded core -- while reinforcing GOP hounding Susan Rice, something that in a sane world you'd think they'd want so forgotten in the public mind that they'd try to find one of those memory-eraser flash devices from Men in Black.
5) Chuck Hagel is going to get confirmed. He's two vote short, and two Republicans are on record as saying they'll switch their votes in 10 days, after vacation. So, Republicans are solidifying their reputation of spiteful petulance as the "Party of No," a party with no agenda, just having the ability to whine, obstruct, filibuster and stifle the country to keep it gridlocked -- all for nothing. All for no benefit, at least if they're trying to actually expand their party and not just fortify their radical far-right base...which is what lost them the last two presidential elections.
6) It's monumentally stupid just because. Just because it sets the country down a very bad path. Just because you know it'll be used against them. Just because it's not based on substance, but a vindictive desire to embarrass. Just because it doesn't pass the smell test. Just because.
There is no upside to this for Republicans. Strengthening their base doesn't cut it anymore. Even Republicans have acknowledged that their challenge is to expand their party. That's why this is just nuts. Filibustering a Defense Secretary nominee for the first time in U.S. history -- for an opposition party candidate, in a position as critical as Secretary of Defense, who is going to get confirmed, after you already blocked a black woman -- is just bizarre. And once again, Republicans show that they are their own worst enemy.
At least we now can better grasp why, when President Obama said at this State of the Union Address -- "Can we all agree right here, right now to keep the People's government open" -- Republicans sat on their butts and stayed silent.
It probably makes Harry Reid wonder, though, if perhaps he should have been tougher on changing the filibuster rule, and not trust that whole "gentlemen's agreement" thing to act like gentlemen and get nominees through quicker...