Reigning champions United are currently seventh in the table with 37 points from 21 games, five points behind fourth-placed Liverpool.
The Red Devils play five top-flight matches between now and mid-February, a sequence that starts with Sunday's trip to third-placed Chelsea and ends with a clash with current table-toppers Arsenal at the Emirates Stadium.
And Vidic said in an exclusive interview in the latest issue of Inside United magazine: "We have to win regularly and in the next month we will know exactly where we are.
"By the end of January and start of February we will show what our position is and what our capability is in the Premier League.
"Then, of course, the Champions League starts up again. This is an important time for us and we all want to do well."
United are away against Olympiacos in the first leg of their Champions League last-16 tie on February 25.
In other cup action, they play the second leg of their Capital One Cup semi-final with Sunderland at Old Trafford next week, starting the contest 2-1 down from leg one.
The Red Devils have struggled for consistency in manager David Moyes' first season in charge.
And while Vidic has described Moyes as a "good character" for keeping the group going, the centre-back has also emphasised the responsibility of the players, not least himself.
The 32-year-old Serbian said: "You have to always be together as a team.
"That's important. If you have a bad result you have to concentrate on doing the right things - in training and with your behaviour, then in the matches.
"You try to lead by example first in the dressing room, then out on the pitch.
"We are lucky here because there are so many players who are experienced and mature people, they help the team try to achieve what we want to do."
He added: "You have to respect your team-mates; if you respect them, you get respect back. You support them, talk to them, encourage them if needed.
"The manager is a good character and does that but it's up to the players too. We're a group and it's a group responsibility to deal with those situations."