See I would have said 7 months was way too young, but thats my opinion. I would rather put the early months of a lurchers life into obedience training making sure the pup was 100% sound at fetching, coming back, standing, jumping ect ect ect. Seen it loads of times disobedient dogs running a mock in the fields and their owners getting very angry, but to me the owner is to blame. Also seen them bark when turning caused by frustration by being brought on too young.
Not saying whats right or wrong just trying to get as many honest opinions from people, whilst having a good debate.