I think you might find it quite hard to find an apartment in Delhi for such a short period of time. There is a lot of demand for expat housing in Delhi and therefore landlords capitalise on this to look for tenants who can commit for at least a year. This saves them haing to look for another tenant.
Take a look at our Accomodation in Delhi page for more information on the housing situation in Delhi.
It could be an idea if you look at staying at cheaper hotel, BnB or apart-hotel. There are lots of websites that will give you special offers.
Best of luck with your search.