I would wait till the grounds soft..
I would be sick knocking up a young dogs toe this time of year, when the seasons around the corner..
Its personal choice regarding uping the bag..
A analogy would be its easier to over cook something.. Under do it and if its not quite there, give it a bit longer..
The handler should gauge the dogs maturity and ability, to hopefully make the best decision for the young dog...
I have a 14 month old dog that's seen nothing.. I aint fussed one bit about it