In case of house property,Pre Construction Interest is the interest paid by the assessee till the year of completion of construction and one point to be considered is interest paid in the year in which construction is completed can not be regarded as pre construction interest. so here when the construction is completed is relevant but not when u occupied such property is immaterial.so for eg: if u construct ur house with in 3 years and interest paid is as follows
2007-08 : 15000
2008-09 : 5000
2009-10 : 5000(construction is completed)
in the above case,interest paid in 2007-08 and 2008-09 should be considered as preconstruction interest i.e rs 20000 only
and interest limit for self occupied property i.e 30000 or 150000 as the case may be is for both Interest and Pre construction Interest