After the final renovations, we witnessed a flurry of interest, ultimately selling above the asking price!

I didn't budge and declined additional credits.They finally sent a termination notice but checking with their lawyer regarding request of earnest money. 

@Joseph Chiofalo has some great nationwide STR investment loan products and fixed rate second/Helocs for investors loans clients tapped into recently. 

Is this a good strategy that actually reduces the life of the loan?

Since we will not be doing the work until later on, would it make more sense to use the 504 to purchase the property only right now, then seek another loan or LOC when we are ready to begin the work?

Current loan is 420k and value at 545k, credit score 740+.

I needed all of them  RE license to sell RE  Mortgage to do private loans in the states that require it.. and contractors to build the homes I am building and then on top of that I have a developers license in Oregon ( no test required just a money grab And when I was figuring out what I wanted to do I got my pilots license around 20 too.. as I really wanted to be an airline pilot.. but alas in those days it was very hard to get hired not like today.

Perform a final walkthrough of the property prior to closing to ensure the condition of the property hasn't changed since it was inspected.9.

If using high LTV loan and legit underwriting, the purchase will have negative initial cash flow.  

This might entail buying a single-family home with rental potential and living in one area while renting out the other units, or it could entail buying a multifamily property and living in one apartment while renting out the others.Financing Options: Look into traditional mortgages, FHA loans (for home hacking), and other inventive financing techniques.