What Ed Llarena from Philippines stated is a valid point. But in India, under the labour laws, no such time limit is prescribed. Hence the disciplinary proceedings must be commenced as and when the same is brought to the notice of the concerned authorities. A final decision on the matter has to be taken without any influence by the concerned disciplinary authority as soon as either the guilt is admitted by the accused or the inquiry report is received, which ever is earlier.
A situation like fraud, etc might require time to very the documents and bring out the evidences. So as Nathrao said "Taking time to do the homework of getting evidence and verifying facts before taking action can be justified, " . But I do not agree with the last part of the sentence "if there is a documentary trail", as this is the responsibility of the presenting officer in an inquiry.