Its 60 days from the date of closing for primary residence, the general rule applies to most primary occupancy conventional, FHA, and VA loans. 

That won't apply to 95% of the rehabbers.

My boyfriend and I are new property owners and are working to fill a vacant unit.There are a couple of girls (two cousins and one's newborn son), who have seen the property/unit and applied to live there.

This is NJ law so applies statewide.

However, it definitely taught me a lot about the guts of a company and those principles that can be applied to every company out there. 

and you can apply that knowledge to the next one. 

As well as applying these concepts and understanding them fully.Many have been very successful without it but I say its the best foundation to real estate you can get.

If I lease my house for one year tomorrow can I then go in and apply for the FHA loan or do I need to wait until it has been rented for one year.

My other property was not a rehab and I had plumbing issues there due to clogged sewer lines because the tree roots grew into the sewer lines under my front yard. 

Did you apply closed/open cell spray foam - or strap and use packed cellulose/hemp/fibre - the outer walls and underside of the roof deck (requiring an over roof) or did you maintain ventilation under the roof-deck and insulate over your ceiling?