The Black Cats are five points adrift of safety at the bottom of the Premier League table having made 14 summer signings under former manager Paolo Di Canio, and go into Wednesday night's game with Chelsea off the back of a goalless draw at Aston Villa at the weekend.
"We are making progress but I don't know how long it will take, you need time," said Poyet. "If I had not seen what I saw on Saturday I would be more worried. The way we trained and planned the game, there were encouraging signs.
"When you are coming close to January you are thinking what you need to do. The more the team improves the fewer changes you will see. There is a limit. I cannot go until December 28 waiting to see positive signs. So the next few weeks are important, deciding if we need two new players or five.
"It is not like I am not going to bring anyone in, I will. But depending on the next two or three weeks it could change the number [of transfers] I make. If we don't keep improving we need a bigger shake up. It is a way of saying 'It depends on the player'."
You can get live coverage of Sunderland vs. Chelsea from the Stadium of Light with Sports Mole from 6.45pm tonight.