Maddy bhates doing her teeth now & she's getting Adult teeth, I used to just let her chew or whatever on her baby brush but at age 2ish I started making sure she actually brushed it..
I know the Milk Teeth paste, I think I only started using tooth paste opnce she was 2-3yrs?? I cant rememnber it was SO long ago!!!

Maybe put her toothbrush in the bath already when you fill it up, so it's already in there when she hops in & just leave it there for her... to do whatever she does with it...??

GL