You can provide the bird with a bowl of water that it can get into & clean itself, when it wants to.....you don't have to wait any length of time.....no soap or shampoo on the bird though.....
Not to worry, there is nothing unhygenic about the bird bathing when it is ready.....
You have a young bird, so maybe keeping the bird at 40F or warmer for bathing would be OK.....healthy, grown birds can handle temperatures around 0C without any problems.....