As millennials postpone life's major milestones, grabbing their attention has proven a bit elusive for home improvement retailers.

But now, as the older members of this generation start reaching the median age for first-time homebuyers, the industry is starting to see how their tastes differ from their predecessors — and likewise, how they'll need to evolve their businesses to suit these shoppers' needs.

Near the top of millennials' wish lists are smart, energy-efficient homes with an inspiring outdoor space. Yet most important for this cohort, which is already known for its desire to stand out, is finding a way to use their homes as a means of self-expression.

"[Millennials are] a lot more focused on bringing some personality into the home," Kevin Hofmann, Home Depot's chief marketing officer, told CNBC.

On a call with analysts in May, Home Depot CEO Craig Menear said millennials appear to be in a six-year delayed cycle for forming their own households. Indeed, the median age of first-time homebuyers reached 35 between 2010 and 2015, according to PwC. That's an all-time high since the firm started tracking this metric in 1970. And just last week, a report from the U.S. Census Bureau found the country's homeownership rate hit its lowest level since 1965.

Yet even as the generation holds onto urban living as long as possible — namely, until they become parents and have to send their kids to school — they are showing an inevitable desire to move back to the suburbs, PwC's Byron Carlock said.

"It's really not a question of 'if,' but rather a question of 'when,'" said UBS analyst Michael Lasser, who has a buy rating on Home Depot's stock.