Based on how well Ukraine has defended itself, I suspect that despite all of his almost-apparently-naïve "don't panic" talk, very much was being done to ensure that the country was prepared. Maybe delaying the very visible actions of conscription and training was to maintain a façade of lack of preparation.

On the other hand, maybe the invaders are doing poorly simply because Russia did plenty of conscription, but no training or preparation.

They didn't. Ukraine has had compulsory military service since 2014 so most men do have military training.