Northeast Roberts is in Downtown Gresham. If you look at it on Google Maps, it is a few minutes from the Best Buy on Division (Gresham Station). If you go South on Roberts and East on Powell, It would be about an 8 to 10 minute drive to the complex both parties had their apartments at. Their apartments were off of Hwy 26. So the timeline would be August 2011 in Roberts Street Apartments. I am guessing May of 2012 JH and AH moved next door to WH and CH, based on a Facebook comment date left on one of WH photos.
BBM... just a minor point of clarification if no one's mentioned this yet. Unless the Holts moved twice, once next door to WH and CH and then another move in the same complex, they didn't live next door to each other. Same complex, but different buildings and apparently across the parking lot from each other.
http://www.oregonlive.com/gresham/index.ssf/2012/10/news_of_whitney_heichels_death.html
Snippet, BBM:
"The only sign that tragedy had made a home here was the small memorial laid out next to the Heichels door. A collection of candles had melted into themselves, flowers were propped up along the wall and a piece of black foam board, full of messages, was attached to the door frame.
<snip>
Just across the parking lot, in another of the complex's buildings was a second door, this one belonging to Jonathan Holt, the man police have arrested in connection with Heichels killing."