D.W.
I really don't think you can rapidly train them unless they are ready. Your son is very, very young. Is he showing any signs of readiness? Does he stay dry for periods of time? You can't make their body physically mature because they need to go to school.
You can test him and try things like going bare bottom and setting an alarm for every 15 minutes in the beginning. Expect the first week to be messy, see how he does the second week. If he's just not getting it you may need to look for a daycare that doesn't require such a young child to be trained.
There is no way my son was ready at that age but my daughter started showing signs at 17 months. Now we are completely diaper free at home except for nap and night. And she has started staying dry while we are out and about at times.