im just wondering if the interview is finish will the immigration will remain me to stay in hk?

i have my dependant interview on 30 of april here in hk,and im just wondering that if the interview is finish will the immigration will remain me to stay here in hk to wait for my visa while on processing or should be leave hk before the expiration of my tourist visa?bec,the immigration give me a letter that i can stay here in hk at present but no work and studies at all.wondering if that is only until 30 or to wait for outcome of dependant visa?ty