Should i keep looking for a job or wait for a reply first?

So basically i have to look for a work experience before the Monday 13th October. And i called for a aged care and a lady tell me that she will talk to their manager and give me a reply next week. The problem is that if they reject me, i might not have enough time to get another placement before the Monday. So i think it might be better for me to look for other placements too. But if the aged care decided to take me and some other work place accept me as well, then i will have to reject the aged care. And i don't know how to do that without sounding mean. And i don't want them to go through all the trouble for me and tell me that i can do work experience at their place but then i ended up rejecting them. What is the best thing to do in this situation?