Rent with an option to buy does not offer you as much protection as a land contract, seller’s lien, contract-for-deed, whatever it is called in your area. If the seller is willing to do a lease option and not a contract for deed, why? If you are just trying to call a lease something other than it is for some reason, how much extra are you willing to cough up?
My #1 rule regarding timelines: Whatever you think the timeline is, double or triple it for safety.
I linked you some info below about lease options.
NMLS # 6395
Financing Kentucky One Home at a Time
I answer questions about financing real estate based on my decades of experience dealing with mortgage underwriters. This answer is my personal opinion, has not been reviewed or approved by the company I work for. I do not offer legal or tax advice, if you need answers from an attorney or CPA find one knowledgeable in your local market.