Daryl Horgan, Andy Boyle and Tom Barkhuizen are already in the bag, their moves officially kicking in on New Year’s Day.
Grayson will not rush into the market once the window opens, either in terms of incomings or outgoings.
“We are really pleased with the three we have done, North End boss Grayson told the Evening Post.
“If anyone else becomes available who would improve us, yes we would try and do something.
“At the moment we’ve not got the biggest of squads available because of injuries and suspensions.
“That can change quickly so there is not the need to rush out and make signings.
“As far as moves in the other direction are concerned, no one is likely to go out before the Arsenal game.
“We will assess the squad in mid January and see where we are up to. Some lads might need to go out to get first-team football but I don’t want that to leave us short.
“There is no emergency loan system so you have to make sure you have the necessary cover once the window closes at the end of January.”
Grayson will get his first chance to work with Horgan and Boyle next week.
They are on holiday at the moment, having signed from League of Ireland champions Dundalk.
“The plan is to get them in for a few days before Christmas to meet the players and integrate them into the squad,” said Grayson.
“They will do one or two sessions, then we will get them in between Christmas and New Year for training.
“Potentially they will be available for the Burton game on January 2 and then a nice FA Cup tie with Arsenal.
“Tom Barkhuizen has been training with us for a few weeks now and we are keeping him ticking over.
“We’ve been impressed with him in training and he is another body available to us come January 1.”
Grayson accepts that there is a step up to be made by Boyle and Horgan from the League of Ireland to the Championship.
But their performances in the Europa League have shown him they have what it takes to bridge the gap.
Said Grayson: “What they have both done is prove they can play in Europe against some good teams.
“They have been called up by the Republic of Ireland and Martin O’Neil doesn’t call-up players who he doesn’t think will have a future with him.
“I think that speaks more volumes than perhaps what they did in the League of Ireland, and that is no disrespect to that league.
“There are also gems who have come out of the League of Ireland in the last few years, we would like to think these two can go on to have a really good career here.”