Dear Janet,
As you said, The loan was teken prior to acquire House property.
The interest before acquisition will also be allowed as deduction as the purpose of acquiring HP.
Also refer Explaination to section 24 as mentioned below.
Explanation.—Where the property has been acquired or constructed with borrowed capital, the interest, if any, payable on such capital borrowed for the period prior to the previous year in which the property has been acquired or constructed, as reduced by any part thereof allowed as deduction under any other provision of this Act, shall be deducted under this clause in equal instalments for the said previous year and for each of the four immediately succeeding previous years:
As the property acquired and interest payment belongs to same previous year the whole interest will be allowed as deduction in the same previous year.
No need to divide it in 5 installments.
For your reference i have highlighted few wordings.
If u agree with me click on Thanks user.