The Scotland international saw his 2013/14 campaign ended prematurely by an ankle complaint in March.
He had been nursing a knock prior to that, with a difficult season for all concerned at the Stadium of Light severely disrupted by injury.
Fletcher is, however, well down the comeback trail and Sunderland boss Gus Poyet expects the £12million striker to be an important figure again next term.
He told the Sunderland Echo: "Fletch has been out jogging.
"He's doing well, but, before he goes on holiday, he needs a minimum of two weeks training every day.
"He doesn't have to do it all with us - he can do a lot of it on his own.
"But it will be a few weeks before he can go away, when he's fully recovered."
Poyet added: "He's been out for a while.
"The ankle was in a boot first for some time and then he's needed to start building up his strength, before he has even been able to train.
"He has recovered well, though.
"Normally these kind of injuries fully recover without any problems.
"He had a problem before with that ankle, but he's going to be alright and he will continue to focus on his rehab work."