.- If you need to use the renal income to qualify, tenants will need to be in place with signed leases, security deposit made, etc.- HML often have a hard time giving the new lender an accurate "payoff statement" and verification of on-time payments to them (latter necessary because HML typically do not appear on credit), which can delay the refinance causing (surprise surprise) the HML to get another month and change of interest out of you at the crazy high interest rate.

Total time is usually less than 6 months.

It’s been totally rehabbed but it’s in a frame 2 flat.

I’m only requiring first and security to move in, I’ve left out last months rent.

Just a bilateral agreement that specifies:The giver of the option, or optionorThe receiver of the option, or optioneeThe purchase priceThe term (start date and end date) that the agreement will be in effectThe consideration (typically a dollar amount) paid by the optionee to secure the right to buyPLUS whatever else your attorney thinks is necessary.Make the document recordable by your county clerk, get it signed (and possibly notarized), and then have it recorded on public record.The intent is to ensure that if he tries to sell to anyone else, a title search will find this agreement and trigger a title defect.

Or do I just disclose to the selling agent that I’m an investor and here’s my offer - if it’s accepted, I need X number of days to get secure the funding?

I researched options for a deal I was trying to secure and my understanding is that all maintenance would be on you but for only 20 years at only 4.3%, that certainly seems like it's worth exploring. 

You have promised already to build it. and they are good for the 137 total.

@Ronald Erwin totally unrelated to your question, but why sell the rental and rent your current home?

This interior change forced us to consider the short term rental market and how it could actually be a desirable feature for this market where a group may be interested in renting both sides like adjoining hotel rooms.Our total cash into the renovations was extensive ($95,000).