If you want to borrow a couple we have spares.
With Jenna we started sitting her on the potty at 15mo because we could sometimes tell she needed to go, and she did, and before long she was asking to go verbally. So it could totally be the start for Esther, she's a very aware little girl and I'm sure she'll catch on - and it's GREAT that you're spotting her signals so well on first try.