I am not certain about the game that the opposition is playing. Why they cannot tell the people about the candidate now? We don't want to hear about the candidateS.
I think it is best to tell sooner so that the candidate can have wide exposure to the public and let the public understand him/her better.
Although the campaign has not started officially, the ruling party is gaining a step ahead of the opposition by advertising and promoting the candidate.
Over the past 10-20 years, did the 'no tell' strategy work toward the advantage of the opposition? I afraid the answer is no. So the opposition please wake up! Don't get buried under the old taiji martial art.