Manning is mulling his future following a late-season slide and thigh injury that culminated with a poor performance in the playoffs.
Dennison said he doesn't necessarily have to wait for an answer from Manning to start drawing up his offensive blueprints.
''We're going to see what we do best, see what our team ends up with, there's certainly no rush,'' Dennison said. ''He deserved to take his time and figure out what he wants to do because he's a phenomenal player.''
After saying on Christmas Eve that he intended to return in 2015, Manning backtracked after Denver's 24-13 loss to Indianapolis in the playoffs last month, saying he had to think things over. General manager John Elway asked him not to make a rash decision.
Manning is expected to meet with Elway, team president and CEO Joe Ellis and new coach Gary Kubiak before the Broncos contingent heads to the NFL scouting combine next week.
Manning, who is due $19 million next season, has to have a checkup on his surgically repaired neck at least 10 days before the start of the new league year, which is March 10.
Manning said in Phoenix last month that he expects to pass his physical.
''I don't see that physical being that significant to tell you the truth as far as the revelation out of that,'' Manning said after accepting the Bart Starr award. ''I feel pretty confident that I'll pass that physical and that my neck is in good shape. I'd like to avoid a crowd standing outside the MRI room awaiting the results, if possible. I felt secure about that the past three years and feel the same about that.''
Meanwhile, those close to him, including former coach Tony Dungy, have said they expect Manning to return for an 18th season in the NFL and a fourth in Denver.
Manning, who turns 39 next month, has begun working out with a personal trainer in New Orleans to ascertain his health and fitness should he decide to keep playing.
Asked if he's proceeding as though Manning will return, Dennison said, ''I'm not proceeding with anything. I'm letting him take his time.''
Dennison, who reported to work Monday along with the rest of Kubiak's staff, said he's spoken with each of the Broncos offensive players, including Manning.
''I just said hello to him, just like I said hello to everybody on the offense on our roster,'' Dennison said. ''I just called him up, said hello, introduced myself, told them if they were around just to come in and say hi. No football, no nothing, just say hi.
''I look forward to working with whoever's underneath the roof. John and those guys will give us a good team and we'll go from there.''
Also Tuesday, new defensive coordinator Wade Phillips said he hasn't gotten his fill of football after working for nine NFL teams since 1976.
''I love coaching. That's what I do,'' Phillips said. ''My wife, Laurie, wanted to get me out of the house after a year of being around so I love what I do. I was a lousy head coach, but I'm a pretty good defensive coordinator and that's what I do well. So I wanted to get back to doing that and I couldn't be happier.''
Phillips was hired after the Broncos pursued Cincinnati secondary coach Vance Joseph, who also interviewed for Denver's head coaching job. Joseph was an assistant in Houston for Kubiak and Phillips.
''I think John and Kube and me all feel like Vance is a bright young star,'' Phillips said. ''But I believe I'm of first magnitude myself. I think that's the way they judge brightness of stars, anyway. So it worked out great. It worked out great for me and I think I'm going to do a great job for this team.''
Also, the Broncos announced the hiring of outside linebackers coach Fred Pagac and assistant special teams coach Tony Coaxum.
AP freelancer Michael Kelly contributed.
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