Ahead of his side's trip to face the west London club on Saturday, the Red Devils boss has claimed that the Rs should have moved sooner to hand the Englishman the reins
The 65-year-old took over the reins at Loftus Road on November 24 last year, after Mark Hughes was sacked for leading the Rs to just four points from their opening 12 games.
But, ahead of his side's meeting with the west London club on Saturday, Ferguson has expressed his belief that Redknapp's job might have been easier had he come in sooner.
"It's not easy when you're down at the bottom of the league. Harry will be the first to admit that," the Scot told reporters.
"It may have helped him if he had gone a bit earlier. But with Harry's experience and ability to judge players, he will have a better chance than most in that situation."
The London club have spent heavily this season in an attempt to stave off relegation, but Sir Alex believes that is a risky strategy.
"You can't make money in the Championship. You get the parachute payments, which are terrific I suppose. I don't see why it should apply itself but it is there and teams can benefit from that," he continued.
"But player contracts are an issue because some of them are on very good ones and the clubs have to pay them. If you drop down, I would imagine motivation is very difficult.
"The only place you want to be is the Premier League. That is reflected in QPR spending the money they have."
United have the chance to go 15 points clear at the summit with a win at Loftus Road, but the 71-year-old is under no illusions about the difficulties of facing the league's bottom side.
"We are going down there hoping to win. That is what our job is," said Ferguson.
"QPR are fighting for survival and we know it is going to be a hard. But that type of thing is what we need anyway. We need to keep the awareness on making sure we do our job right.
"These games have to be treated exactly as we would Real Madrid or anyone else. That is the only way we can approach them.
"But there is a brilliant spirit in the place and a good determination. With the right attitude and the right players we have a chance."