Fury's long lay-off included a backdated two-year ban from UK Anti-Doping in December after he was charged with testing positive for a "prohibited substance" in June 2016.
Warren, though, believes Fury needs "three or four fights" before being ready to take on Joshua.
Fury has not fought in two and a half years since beating Wladimir Klitschko in November 2015 to win the IBF, IBO, WBA and WBO titles.
Fury also suggested Joshua, who now holds the WBA, WBO, IBF and IBO championship belts, is now second fiddle to American WBC king Deontay Wilder in the division.
But Fury was soon stripped of the IBF belt, and relinquished the WBA and WBO versions amid mental health issues. "He is looking for one punch all night".
"I'm the fittest I've ever been".
"Anyone who moves a bit and throws a few feints, he can't deal with". I'd outbox him for a few rounds then knock him out.
"I am certain the boxing public - who he never lost the affection of - will get behind him in force and support his journey - starting at the Manchester Arena on June 9th". "The reflexes are as good as they've ever been".
He, however, prefers to fight Wilder next. "I kid you not", he added.
In the meantime, we'll have to wait and see who Fury's first opponent will be.
Should Fury prove victorious in his comeback effort, it will be interesting to see whether he can interrupt the best-laid plans of the division now that unified champion Anthony Joshua (21-0, 20 KOs) and fellow unbeaten WBC champion Deontay Wilder (40-0, 39 KOs) appear on a collision course to face each other.
"Until he makes his return to the ring, I can not sit down and wait patiently at home for Tyson Fury's return", Joshua told Sky Sports.
"I needed a new spark and someone with the passion to achieve big goals".
"He has to get himself back in action and worry about what he is doing, rather than sitting at home commentating on my fights".
Former heavyweight boxing champ Tyson Fury explains how the "mac is back" to reclaim the world.