Skipper Gareth McAuley and left-back Ben Thatcher are expected to return to pre-season training later than the rest of the squad due to the medial knee ligament injuries they sustained in the latter stages of the season.
Physio Matt Byard told the club site: "Ben is three weeks into his injury. He's on crutches and the knee is immobilised.
"He will be seeing a specialist soon and then hopefully he will begin swimming and cycling. His injury is going to take about three months before he is back fully, so he is going to have a bit more of an individual-style start to pre-season, but I would envisage him being back playing football again by the middle of July.
"Gareth has a similar injury to Ben, although not as severe, but again it's likely to take around eight to 10 weeks to resolve.
"He will start some rehab work in June, but I would look at him maybe being a week or so behind the rest of the lads when the pre-season programme gets under way."
McAuley has been ruled out of Northern Ireland's friendly with Italy next month.
Town boss Roy Keane is currently deciding where he will be taking the squad for their pre-season tour.