Question re integrating my 1 pet chicken with 1 new chicken in a new environment for both chickens

Until recently, I had 3 chickens. 2 died, leaving 1 behind (an EE who's on the smaller side). I have been searching for weeks now (Craigslist, feedstores, shelters, etc.) for a new companion for her, but no luck. Then one of my husband's co-workers offered us one of her Buff Orpingtons, which she wants us to pick up tonight. According to the co-worker, this Buff is a bit aggressive which worries me some, because my EE is pretty docile but certainly no doormat. Also, note that I just moved to a different house and relocated my 1 chicken to her new chicken coop about 2 weeks ago (so everything is new to her). Both my EE and the Buff are about the same age (EE - 3.5 years old and the Buff about 2 years old). How should I best integrate the two of them? Place the Buff on the roost tonight so they wake up together? Quarantine the Buff first for 30-45 days as others here have suggested? What I am really wondering is whether the fact that everything is new to both of them (new location, new house, etc.), changes how I should integrate them...Can you please advise? Thank you for any insight you can offer.