Sir if you are continuously residing to banglore and took short trips to different states in between then in that case the relevant date shall be the 1st january only as section 47 doesn't provide of computation of the one year so the day you moved vehicle to new state can be considered.
Though in your case there is break that is long in month of April and may and after.that only a short trip so you can take 15 may also as the relevant date for transfer.
47. Assignment of new registration mark on removal to another State-
(1)When a motor vehicle registered in one States has been kept in another State, for a period exceeding twelve months, the owner of the vehicle shall, within such period and in such form containing such particulars as may be prescribed by the Central Government, apply to the registering authority, within whose jurisdiction the vehicle then is, for the assignment of a new registration mark and shall present the certificate of registration to that registering authority.
Provided that an applicant under this sub-section shall be accompanied-
(i) by the no objection certificate obtained under section 48, or
(ii) in a case where no such certificate has been obtained, by-
(a) the receipt obtained under sub-section (2) of section 48; or
(b) the postal acknowledgement received by the owner of the vehicle if he has sent an application in this behalf by registered post acknowledgement due to the registering authority referred to in section 48,
together with a declaration that he has not received any communication from such authority refusing to grant such certificate or requiring him to comply with any direction subject to which such certificate may be granted.
Provided further that, in a case where a motor vehicle is held under a hire purchase, lease or hypothecation agreement, an application under this sub-section shall be accompanied by a no objection certificate from the person with whom such agreement has been entered into, and the provisions of section 51, so far as may be, regarding obtaining of such certificate from the person with whom such agreement has been entered into, shall apply.
(2) The registering authority, to which application is made under sub-section(1), shall after making such verification, as it thinks fit, of the returns, if any, received under section 62, assign the vehicle a registration mark as specified in sub-section (6) of section 41 to be displayed and shown thereafter on the vehicle and shall enter the mark upon the certificate of registration before returning it to the applicant and shall, in communication with the registering authority by whom the vehicle was previously registered, arrange for the transfer of the registration of the vehicle from the records of that registering authority to its own records.
(3) Where a motor vehicle is held under a hire-purchase or lease or hypothecation agreement, the registering authority shall, after assigning the vehicle a registration mark under sub-section (2), inform the person whose name has been specified in the certificate of registration as the person with whom the registered owner has entered into the hire-purchase or lease or hypothecation agreement (by sending to such person a notice by registered post acknowledgement due at the address of such person of such person entered in the certificate of registration the fact of assignment of the said registration mark).
(4) A State Government may make rules under section 65 requiring the owner of a motor vehicle not registered within the State, which is brought into or is for the time being in the State, to furnish to the prescribed authority in the State such information with respect to the motor vehicle and is registration as may be prescribed.
(5) If the owner fails to make an application under sub-section (1) within the period prescribed, the registering authority may, having regard to the circumstances of the case, require the owner to pay, in lieu of any action that may be taken against him under section 177, such amount not exceeding one hundred rupees as may be prescribed under sub-section (7).
Provided that action under section 177 shall be taken against the owner where the owner fails to pay the said amount.
(6) Where the owner has paid the amount under sub-section (5), no action shall be taken against him under him under section 177.
(7) For the purposes of sub-section (5), the State Government may prescribe different amounts having regard to the period of delay on the part of the owner in making an application under sub-section (1)