Deduction related u/s 24 (b)

no you can't until the property is constructed and either it is self acquired or let out

you can claim 24 (b) after the house is constructed. you can claim up to 2 lakhs which includes
1.intetest paid in that year relating to that property
2.it can include pre construction interest (only 1/5 of such interest can be claimed and the balance in the subsequent 5 years)

the total of above 2 can be availed to an extent of 2 lakh and balance interest over and above it will be disallowed