They do not all shout... my GG's certainly scream (and yes I mean scream!), but the BT's are completely quiet... tailwagging, some discharge (sometimes) and when they are outside trying to ride each other.... A billy rag is essential if you do not have your own billy - it can be safely posted inside a double plastic bag and then in a jiffy bag - I have not yet been taken off the Royal mail delivery list!
However one fairly certain method is to put a sponge in (vet will do it for you), take it out after 12 to 14 days, and then two to three days later she will be in season. Billy rag will confirm it (unless you have a GG - you will need ear plugs for those girls!) No PMSG injection required. I have used this method from my first year on, it has so far not failed me and if you have more than one goat to go (and to different places) it is the only way to manage it. It also helps if you have two girls going to the same place - billy will be happy to do it twice!