The T&Cs state that responses should be received within 72 hours (I may be wrong about the timeframe, but it’s certainly less than 10 days). Unfortunately, it is very commonplace for applications to go unacknowledged. I know this myself, having put my heart and soul into applications, only for them to be overlooked and not responded to. It is incredibly disheartening.
I would suggest it is up to you to determine what is an acceptable length of time to wait for a response. For me, if a response isn’t received within a few days, it is usually not a good sign and indicates a lack of communication from the side of the HOs that could be reflected in the way they communicate during sits. At the very least, it is downright disrespectful and I am increasingly withdrawing applications after a few days due to non-response. You may wish to have a look at this thread, which is very helpful and may help you come to a decision about how to proceed: