I'm surprised no one has mentioned it already. And sorry if someone has said this on another thread. It's impossible. However I'd happily offer some long odds for anyone's bet if they don't believe me.
There are a potential 432 points available to be won between now and the completion of 31 games (12 rounds of games X 12 games X 3 points per game). It would be impossible to distribute those points amongst 21 clubs so that the club in 21st position (the position above the relegation places) couldn't be caught by Ipswich. It's a mathematical impossibility. That's even allowing for there being no more drawn games, and those in the relegation spots not picking up any points ensuring the maximum number of points possible going to 21st place and higher.
Even if a club had 0 points at this stage (not 11), and 22nd and 23rd place just had the points gained against the 24th place team and from the game/s between themselves, the earliest the bottom team could conceivably be mathematically down would be around the 29 game mark. And that would only be in the completely absurd situation where the first 21 teams had almost the same points total and there were no drawn games in the first 2/3 of a season. It will never happen! Only scenario would be where a team has had a points deduction.
Sorry for sounding like a numbers geek. If every team maintained their form of the first 19 games over the whole season, Ipswich would be mathematically down with 4-5 games to go. I would say the earliest they might be confirmed as relegated would be late March / beginning of April. Their results may even improve slightly; they can't get much worse!