Dear Babu Grahappravesam is done not for the function part of it but has an important sinificance.The main purpose is to drive out evil effects since the construction materiaals used could be those used in dilipated structures. That is why various hamams are done like GANAPATHY .VASTHU, NAVAGRAHA SUDARSANA ,DANVANTRI HOMAMS. It is not advisable to renyt it out before gp. fINd out if u can come for afew days .,say 1 week .perform gp & rent it out,After all a house is a property aquired for us & prosterity & leave ono chance for any mishappenings.
congrats on ur purchase & my blessings for a happier future
RAMAN MALLI