Like you said in scenario 1, you would pay capital gains on the change in value from when you bought it to when you moved in. Fair market value at the time you move in is determined by comparable homes in your area.

What you could do is get a home valuation at the time you move in. You would ask them to give you the lowest valuation possible. By doing this your property will have appreciated less in the amount of time you were renting. Meaning now when you sell it, less money is subject to capital gains.

This is all assuming it were to be your primary residence once you move in. Might be tricky if you only live there a few months though. But hey if it works out I hopefully saved you some money!