Training pups

Lots of tips on starting young gundog beagles, but I would like more input as i am new to the group. I have hunting beagles that do well in the field. I have 6 young dogs that haven't been started yet. I don't have access to a starting pen but have a hunting area that has lots of rabbits. But is rough...lots of blackberries, briars, vines, etc. I need tips on getting these pups to start a line. I have used tame rabbits in cages, and had some in the field. One of the 6 has now started getting excited (tail wagging, snorting and even sqeaking as he starts the line. I think he is ready to put with other dogs. The others don't seem to be ready to get serious. The pups are from 6 mon to 8mon in age. One is actually over a year and had been out with older dogs on many occasions. She is the least interested in rabbits in the wild. Any suggestions would be appreciated.