Potty training advice

My LO is 18 months and has shown an interest in the toilet. She really hasn’t exhibited any signs. She doesn’t hide to pee or poo. She usually goes poop during her nap or in the morning. She will say “I poop” but it’s not always accurate. So I don’t think she is ready ready but she’s getting there. So I need advice- I want to get a potty for downstairs and then a seat for the upstairs toilet so she can use both. My husband thinks we should just get the seat for the toilet. What worked best for your guys?