When to move on a stage?

[Thecathouse]

Potty training my 21 month old

Day 1 lots of accidents, just kept reinforcing wee wee goes in potty

Day 2 some accidents some on the potty about 50 / 50

Day 3 most on potty, just two accidents today

We are currently on the stage where she is just about the house naked from the waist down.

Would I be right in saying if she goes a day with no accidents it would be right to introduce knickers the next day? With the improvement she is showing that would likely be in a couple days

We did trousers with no knickers as the next stage in training but I'd say see how she's doing by lunchtime tomorrow and you could always pop a pair on after lunch or her nap (if she has one). Sounds like she's making great progress!