Cai, I say go the undies. I know it is tricky if you are going to be in a workplace, but from what I haev seen and heard of Seth he is a fast learner.

Even Charlie only had a few accidents (less than 5?) in jocks before he "got it".

We did a week at home with jocks on (nappies for bed) and by the Wednesday he was done.

It really sounds like Seth is ready.....& if they are ready, it seems to be quick......

Good luck!