The faq at indian consulate SFO website says, one can get the passport on the same day renewed. check this
RENEWAL OF PASSPORTS (EXTENSION OF VALIDITY OF CURRENT PASSPORT)
When are passports renewed ?
What are the requirements for renewing a passport?
How much time will it take?
What would be the duration of the renewal of the passport?
When are passports renewed ?
i) Passports which were issued less than 9 years back such as passports issued in India under the Tatkal scheme
ii) Passports which were issued against lost passports for short validity
iii) But NOT if your passport is completing 10 years / or there is a an F or Final written after the date of expiry- Please apply for new passport in such a case.
What are the requirements for renewing a passport?
i) Original passport
ii) Completed Passport Renewal form
iii) Copy of Green Card (both sides, enlarged clear copy) or Employment Authorization card (clear enlarged copy) or legal/ visa status such as HIB etc
iv) No Fee is payable for renewal but if you are applying by mail, charges for mailing back the passport may be sent through a money order/cashier's check in favor of Consulate General of India. Please see item "VII" of "new passport" requirements.
How much time will it take?
i) If you apply in person at the counter, same day if no prior clearance is required. It may take 30 –35 days if clearance has to be obtained.
ii) If you apply through mail, 3-5 working days, excluding time taken in mail. The proviso regarding clearance mentioned in i) above applies.
What would be the duration of the renewal of the passport?
i) Normally the validity of the passport will be extended up to 10 years from date of its original issue except for persons on BI/ B2 visa or where clearance has not been received from the original passport issuing authority.
ii) In cases of duplicate passports of short validity, renewal will depend upon the legal status of the applicant and receipt of clearance.