Captain sahab, hosla.
Air filter is to be done after 10k-15k kms drivng, based on its condition.
Fuel filter is good for around 80k unless you repeatedly put in dirty fuel.
As for engine overhaul, unless the car overheats, you won't need it for an estimated
250k kms on regular driving, 175k-200k on abusive driving and around 300k-325k on careful and to the book driving