Ryo Hazuki said:
a neo pro is a first year pro and it has always been that, so no dowsett and apollonio aren't and neither is henao. he's been pro since 17
While that may be how you think of it, it's not how it is regulated.
According to UCI regulations a rider is classified as a neo-pro if he is in his twenty-second year when the contract starts (normally 1st of January), and hasn't ridden for a WorldTour or ProConti team before (he may have been on a Continental team). And the "letter of the law" is, as usual with the UCI, somewhat misleading:
The status of new professional is given to any rider who joins a UCI ProTeam or Professional Continental Team for the first time no later than during his twenty-second year.
For the application of this article the date of joining shall be the date on which the rider’s contract comes into force.
The age of the rider is determined by the difference between the year of his hiring and the year of his birth.
A neo-pro keeps that status for 2 years (and his first pro contract has to be for 2 years, too) - even if the contract is terminated (in case of the team folding) and he goes to a different team.