Sorry dear, you have to complete your 10+2 before appearing in NEET-UG examination. And the minimum age is 17 years as on 31st December, 2018.

The minimum criteria for applying for Neet ug is intermediate passout, with the minimum percentage of qualification of respected category to which a candidate belongs to.
The Age criteria for appearing in NEET (UG) - 2018 is as follows:
For Candidates of Unreserved Category (UR) born on or between 07.05.1993 and 01.01.2002.

For Candidates of SC/ST/OBC/PH Category  born on or between 07.05.1988 and 01.01.2002

ELIGIBILITY FOR SEATS UNDER THE CONTROL OF STATES/ DEEMED UNIVERSITIES/CENTRAL UNIVERSITIES /SEATS OF ESIC & AFMC INCLUDING BHU & AMU/CENTRAL POOL QUOTA  -->
Indian Nationals, Non Resident Indians (NRIs), Overseas Citizen of India (OCIs), Persons with Indian Origin (PIOs) & Foreign Nationals are eligible for admission in Medical/Dental Colleges subject to rules and regulations framed by the respective State Governments, Institution and the Government of India.
(b) Foreign nationals may confirm their eligibility from the concerned Medical/Dentals College/State. 

ELIGIBILITY FOR 15% ALL INDIA QUOTA SEATS (a) Indian Nationals, Non Resident Indians (NRIs), Overseas Citizen of India (OCIs), Persons with Indian Origin (PIOs) & Foreign Nationals are eligible for 15% All India Quota Seats.

No, it is not possible this is because the eligibility criteria mentions that the student must pass 10+2.

Sorry but you'll have to wait till you become 17 and give your boards. 

National Eligibility cum Entrance Test

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