When to start potty training?

My one-year-old will not quit taking her diaper off. I put clothes on her to keep her diaper on, and she gets out of them& her diaper. I’m at a loss. No matter if she has a clean diaper or not, I’m putting a diaper back on her all through the night. If I lay down, I’m right back up, putting another on. Every 20/30 mins. Now she’s starting to play in her poop. Any chance she gets. If she poops through the night, she’s in it before I catch it. I’m so exhausted with cleaning up poop mess, lol. Please tell me, is this Normal? And how can I fix it? I also have a five-year-old, and I’ve never had to deal with this with her. Has anyone started potty training at 1 & been successful? She’s 15 months.