I've been playing since patch 3.2 and this has been a common practice in Diabolos (not so much atm, hunting is kinda dead). In all honesty it just depends on who is on. The norm is that either someone will scout the hunts before hand and once they are all found the train will start or a train starts and everyone starts scouting going from one zone to the next. They usually wait a good 2-3mins before pulling the first hunt so ppl can come, sometimes longer depending if ppl are still coming. Every hunt is shouted in order and after every kill so the train always knows where to go next. The train then waits a usual 1-2mins at this point as anyone who actually cared to join the train has already joined. If someone still needs a party or a party is too small a few nice ppl will actual leave their party to form a new party or join the undersized party so all get full credit. This is all for 4.0 hunts, 2.0 and 3.0 hunts specifically
A Ranks aren't as friendly since not may care to do them so usually once called ppl don't wait as long before killing since they it is expected that no many will actually show. S Ranks no matter what level always pull in a crowd but for 2.0 the general idea is first come first serve since they die so fast so landing a hit before it dies can be competitive.
There are snipers and earlier pullers on diabolos but they usually aren't that big of an issue. My biggest advice would be to try and join a few hunt LS so you always know what hunts are up and make a macro hunt shout for all your LSs and the world so more ppl know what hunts are currently being targeted. Let your party know to shout for you that they have someone otw. If Hyperion has enough etiquette then they should be willing to wait till everyone is there. Also if you haven't lower your graphic settings and turn visual effects offs at least for non party members. Your response time should improve.