United tackle Arsenal on Sunday and fellow Premier League title rivals Chelsea the weekend after with the return European leg against Schalke sandwiched in between.
"I hope we get a positive result on Sunday against Arsenal and then from there, depending on that result, I may well make three changes for next week's second leg as we've got Chelsea the weekend after," said Ferguson.
"It's a crucial seven days coming up for the club. I think we've come to our peak."
United are on the verge of a record 19th English league title, standing six points ahead of Chelsea and nine in front of Arsenal with just four matches left.
And after Tuesday's impressive win, they are virtually assured of a place in the May 28 final of the Champions League where either Barcelona or Real Madrid will be their opponents.
Schalke goalkeeper Manuel Neuer, a reported United target, kept the three-time champions at bay almost single-handedly on Tuesday before quick-fire second-half goals from Ryan Giggs and Wayne Rooney brought United victory.
The result puts Ferguson's side firmly in the driving seat ahead of next week's return leg at Old Trafford, when they will seek to book their place in the Champions League final for the third time in four seasons.
"It was a very professional performance tonight," added Ferguson. "The concentration, intensity and passing were all top class. They have all done fantastically well."
Neuer admitted that United were just too good.
"We had too much respect for our opponents," said Neuer.
"We weren't compact enough, we weren't aggressive in the tackles. We can be proud of what we have done. We will try and keep the adventure going to the end."
Ferguson was impressed by Neuer, who seems set to move to Bayern Munich in the summer.
"Manuel Neuer was incredible, it was perhaps the best performance I have seen by a keeper against us in my career."
Rooney, sent off on his last appearance at this venue in the 2006 World Cup, believes United could have scored more goals after dominating from the early stages.
"We're delighted but a bit disappointed in terms of not scoring more," he said.
"We have done very well. We have to be professional for the second leg as Schalke can't be taken lightly. They went to Inter and won 5-2 (in the first leg of their quarter-final)."
Giggs was always confident of victory.
"I thought if we kept creating chances then they would go in," said the Welshman who, at 37, became the oldest player to score a Champions League goal.
"We could have been four or five up at half-time. Before the match we would have taken 2-0 but it's quite disappointing in terms of the final result now."
Schalke defender Christoph Metzelder admitted his side were outplayed.
"We have to recognise that we were dominated by a team playing in a different dimension," he said. "We still have hope, anything is possible. We'll try and do everything to win at Old Trafford."
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