I don't know much about proprietary leases but apparently it's an issue for a co-op I'm thinking about making an offer on.I'm getting a mortgage through my bank, and when I approached them to check the financials on this particular apartment, they said the project was declined because it has a proprietary lease that expires in less than 30 years.

The only exceptions are if you live in a SW state (loads of sunlight) that has significant tax credits to offset installation costs (they've mostly all expired as of 2016), and your local utility will let you install a net meter to sell back unused power to them (make sure they'll buy it at the same cost as they sell to you!). 

are there any stats that go along with this as to what the best time to age the expireds is?

Apparently, there is an existing contract in place that expires in 4 or 5 years. 

In addition to expired listings why not look at old listings?

If they are tenants, you simply have to give them 30 day notice (the tenants in foreclosure protection act expired), you don't have to honor a lease, after the 30 days, you can evict. 

Her note balloons or expires in 2017. 

Put the expiration date 20 years in the future.

Better off waiting until the contract expires.

@Abhilash JosephThe first step in Texas is a 3 Day Notice to Vacate/Terminate which needs to be delivered by one of the following methods:In PersonTaped to the inside of the front doorCertified Mail along with regular mailUpon service and expiration of the 3 days, the eviction can be filed in the proper JP court.